Solutions Key Probability and Statistics 11 CHAPTER ARE YOU READY? PAGE 791 1. B 2. E 3. A 4. C 5. 6. 1 - 14 ___ 20 = 20 ___ 20 - 14 ___ 20 = 6 ___ 20 = 3 ___ 10 7. 3 __ 8 + 5 __ 6 = 9 ___ 24 + 20 ___ 24 = 29 ___ 24 8. 8 ___ 15 - 2 __ 5 = 8 ___ 15 - 6 ___ 15 = 2 ___ 15 9. 1 ___ 12 + 1 ___ 10 = 5 ___ 60 + 6 ___ 60 = 11 ___ 60 10. 1 __ 2 · 3 __ 7 = 3 ___ 14 11. 2 1 __ 3 · 1 __ 4 = 7 __ 3 · 1 __ 4 = 7 ___ 12 12. 4 __ 5 ÷ 1 __ 2 = 4 __ 5 · 2 __ 1 = 8 __ 5 13. 5 1 __ 3 ÷ 1 __ 4 = 16 ___ 3 ÷ 1 __ 4 = 16 ___ 3 · 4 __ 1 = 64 ___ 3 14. 7% of 150 = x 0.07(150) = x x = 10.5 15. 90% of x = 45 0.9x = 45 x = 50 16. Price increased by 12% of 24 = 0.12(24) = $2.88 17. The amount of water to be changed is 20% of 65 = 0.20(65) = 13 gal. 18. 2, 4, 4, 6, 9 mean: 5 median: 4 mode: 4 19. 1, 1, 1, 2, 2, 2 mean: 1.5 median: 1.5 mode: 1, 2 20. 1, 2, 3, 4, 5, 6 mean: 3.5 median: 3.5 mode: none 21. 3, 14, 14, 18, 18, 18, 20 mean: 15 median: 18 mode: 18 11-1 PERMUTATIONS AND COMBINATIONS, PAGES 794–800 CHECK IT OUT! 1a. start plot end 6 × 4 × 5 = 120 There are 120 adventures. b. letter letter letter letter digit 52 × 52 × 52 × 52 × 10 = 73,116,160 There are 73,116,160 possible passwords. 2a. 8 P 3 = 8! _______ (8 - 3)! = 8! __ 5! = 8 · 7 · 6 · 5 · 4 · 3 · 2 · 1 ____________________ 5 · 4 · 3 · 2 · 1 = 8 · 7 · 6 = 336 There are 336 ways to award the costumes. b. 5 P 2 = 5! _______ (5 - 2)! = 5! __ 3! = 5 · 4 · 3 · 2 · 1 ____________ 3 · 2 · 1 = 5 · 4 = 20 There are 20 ways a 2-digit number can be formed. 3. The order does not matter. It is a combination. 8 C 2 = 8! ________ 2!(8 - 2)! = 8! ____ 2!6! = 8 · 7 · 6 · 5 · 4 · 3 · 2 · 1 ____________________ 2 · 1(6 · 5 · 4 · 3 · 2 · 1) = 8 · 7 ____ 2 · 1 = 28 There are 28 ways to select 2 swimmers from 8. THINK AND DISCUSS 1. Possible answer: selecting a 9-player batting order from 20 players; selecting 3 magazine subscriptions from a list of 20 2. 1; possible answer: there is only 1 way to choose the entire group from a group. 3. Possible answer: the number of ways to select 4 items from 3; you can’t select more than the total number of items. 4. EXERCISES GUIDED PRACTICE 1. important; permutation 2. blouse jacket skirt 3 × 3 × 2 = 18 There are 18 different outfits. 3. digit letter 9 × 25 = 225 There are 225 different codes. 4. 7 P 2 = 7! _______ (7 - 2)! = 7! __ 5! = 7 · 6 = 42 There are 42 ways to schedule the 2 activities. 405 Holt McDougal Algebra 2
24
Embed
CHAPTER Solutions Key 11 Probability and Statistics · Solutions Key 11 Probability and Statistics CHAPTER ARE YOU READY? PAGE 791 1. ... 11-2 THEORETICAL AND EXPERIMENTAL PROBABILITY,
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Solutions Key
Probability and Statistics11
CHAPTER
ARE YOU READY? PAGE 791
1. B 2. E
3. A 4. C
5.
6. 1 - 14___20
= 20___20
- 14___20
= 6___20
= 3___10
7.3__8
+ 5__6
= 9___24
+ 20___24
= 29___24
8.8___
15- 2__
5= 8___
15- 6___
15
= 2___15
9.1___
12+ 1___
10= 5___
60+ 6___
60
= 11___60
10.1__2
· 3__7
= 3___14
11. 2 1__3
· 1__4
= 7__3
· 1__4
= 7___12
12.4__5
÷ 1__2
= 4__5
· 2__1
= 8__5
13. 5 1__3
÷ 1__4
= 16___3
÷ 1__4
= 16___3
· 4__1
= 64___3
14. 7% of 150 = x
0.07(150) = x
x = 10.5
15. 90% of x = 45 0.9x = 45
x = 50
16. Price increased by 12% of 24 = 0.12(24) = $2.88
17. The amount of water to be changed is 20% of 65 = 0.20(65) = 13 gal.
31. The Es in GEESE are identical. The order of the Es
is not important.
32. Number of sequences in a peal is 8! = 40,320.
It would take 0.25(40,320) = 10,080 s = 2.8 h to
ring a complete peal.
33a. President A A A A A A A A A A A A
Vice President B B B C C C D D D E E E
Secretary C D E B D E B C E B C D
b. President B B B B B B B B B B B B
Vice President A A A C C C D D D E E E
Secretary C D E A D E A C E A C D
A president, a vice president, and a secretary can
be chosen in 60 ways.
c.5!_______
(5 - 3)!= 60
d.5!________
3!(5 - 3)!= 10
The answer 60 is a number of permutations, and
the answer 10 is a number of combinations.
34. Possible answer:
n P r____ n C r
=
n!______(n - r)!________
n!_______r!(n - r)!
= n!______(n - r)!
× r !(n - r)!________
n!= r !;
6 P3____ 6 C3
= 3! = 6; 6 C3 = 6 P3____3!
;
the number of combinations of n items taken r at
a time, is the number of permutations of the items
divided by the number of ways to order the r items.
35. 9 C2 = 9!________
2!(9 - 2)!=
9!____2!7!
= 9 · 8____2 · 1
= 36;
9 C7 = 9!________
7!(9 - 7)!=
9!____7!2!
= 9 · 8____2 · 1
= 36;
10 C6 = 10!_________
6!(10 - 6)!=
10!____6!4!
= 10 · 9 · 8 · 7
___________ 4 · 3 · 2 · 1
= 210;
10 C4 = 10!_________
4!(10 - 4)!=
10!____4!6!
= 10 · 9 · 8 · 7
___________ 4 · 3 · 2 · 1
= 210;
n!________r !(n - r)!
is the same as n !________(n - r)! r !
.
36a. Jen can arrange the dice in 5! = 120 ways.
b. 5 C3 = 5!________
3!(5 - 3)!=
5!____3!2!
= 5 · 4____2 · 1
= 10
37. A; order is important.
38. Choosing 3 times from 9 digits: there are 9 possible
choices the first time, 8 the second, and 7 the third.
The total number of permutations is
9 × 8 × 7 = 504.
TEST PREP
39. D
14 C5 = 14!_________5!(14 - 5)!
= 14!____5!9!
40. J
9 C4 = 9!________
4!(9 - 4)!=
9!____4!5!
9 C5 = 9!________
5!(9 - 5)!=
9!____5!4!
41. 15 C4 = 15!_________
4!(15 - 4)!=
15!_____4!11!
= 15 · 14 · 13 · 12
______________ 4 · 3 · 2 · 1
= 1365
There are 1365 ways Rene can choose her
electives.
CHALLENGE AND EXTEND
42a. 4 points: 4!________2!(4 - 2)!
= 4!____2!2!
= 4 · 3____2 · 1
= 6
5 points: 5!________
2!(5 - 2)!=
5!____2!3!
= 5 · 4____2 · 1
= 10
6 points: 6!________
2!(6 - 2)!=
6!____2!4!
= 6 · 5____2 · 1
= 15
n points: n C2
b. 20 points: 20 C2 = 20!_________
2!(20 - 2)!=
20!_____2!18!
= 20 · 19______2 · 1
= 190
43. Select 12 jurors out of 30 potential jurors, 30 C12.
Select 2 alternate jurors out of the remaining
18 potential jurors, 18 C2 . Use the Fundamental
Counting Principle to combine the number of ways
the jurors can be selected, (30 C12 ) ( 18 C2 ).
SPIRAL REVIEW
44. p(x) = 0.15x; P(x) = 0.45x
P(x) = 3p(x) is a vertical stretch.
45. 17___n= 11___
77 1309 = 11n1309_____
11= 11n____
11 119 = n
46. 2.9___3.7
= x_____23.31
67.599 = 3.7x67.599______
3.7=
3.7x____3.7
18.27 = x
407 Holt McDougal Algebra 2
47. 2.2___n
= 1.6___9.5
20.9 = 1.6n
20.9____1.6
= 1.6n____1.6
13.0625 = n
48. x___36
= 98___18
18x = 352818x____18
= 3528_____18
x = 196
49. A = 6, B = 3, C = -9
B2 - 4AC = 3
2 - 4(6)(-9)
= 225
Because B2 - 4AC > 0, the equation represents a
hyperbola.
50. A = 8, B = 0, C = 8
B2 - 4AC = 0
2 - 4(8)(8)
= -256
Because B2 - 4AC < 0 and A = C, the equation
represents a circle.
11-2 THEORETICAL AND EXPERIMENTAL
PROBABILITY, PAGES 802–809
CHECK IT OUT!
1a. There are 36 possible outcomes, and 5 outcomes
with the sum of 6.
P(sum is 6) = 5___
36
b. There are 36 possible outcomes, and 0 outcomes
with a difference of 6.
P(difference is 6) = 0___36
= 0
c. There are 36 possible outcomes, and 15 outcomes
where the red cube is greater.
P(red cube is greater) = 15___36
= 5___12
2. There are 100 possible outcomes.
The number of possible outcomes where both
numbers are less than 9 is(first number < 9) (second number < 9) = 8 × 8 = 64.
P(both numbers less than 9) = 64____
100=
16___25
The probability that both numbers are less
than 9 is 16___25
.
3. Order is not important. It is a combination.
The number of possible outcomes is
8 C2 = 8!____
2!6!=
8 · 7____2 · 1
= 28.
There is only 1 way to play both of the retailer’s ads.
P(play both of the retailer’s ads) = 1___28
4. Area of large triangle is At = 1__2
(15)(15) = 112.5.
Area of small triangle is As = 1__2
(4)(4) = 8.
As___At
= 8_____
112.5=
16____225
The probability that the point is in the small triangle
is 16____225
.
5a. P(diamond) = 9___
26
b. P(not club) = 1 - P(club)
= 1 - 7___26
= 19___26
THINK AND DISCUSS
1. No, the probability of an event cannot exceed 1.
2. sum of 5 and sum of 9
3. experimental: 8___20
= 2__5
; theoretical: 1__2
4.
EXERCISES
GUIDED PRACTICE
1. theoretical probability
2. There are 8 possible outcomes, and 4 outcomes
where the quarter shows heads.
P(quarter shows heads) = 4__8= 1__
2
3. There are 8 possible outcomes, and 2 outcomes
where the penny and the nickel both show heads.
P(penny and nickel show heads) = 2__8= 1__
4
4. There are 8 possible outcomes, and 3 outcomes
where 1 coin shows heads.
P(one coin shows heads) = 3__8
5. There are 8 possible outcomes, and 2 outcomes
where all coins land the same way.
P(all coins land the same way) = 2__8= 1__
4
6. P(does not end in 5) = 1 - P(ends in 5)
= 1 - 10____100
= 9___10
The probability that a random 2-digit number does
not end in 5 is 9___10
.
7. P(not in Dec or Jan) = 1 - P(in Dec or Jan)
= 1 - 31 + 31_______
365=
303____365
The probability that a date is not in December or
January is 303____365
.
8. Order is important. It is a permutation.
The number of possible outcomes is
4 P4 = 4!__0!= 24.
There is only 1 way to place all the letters in the
correct envelope.
P(all letters are in correct envelopes) = 1___24
408 Holt McDougal Algebra 2
9. Order is not important. It is a combination.
The number of possible outcomes is
12 C3 = 12!____3!9!
= 12 · 11 · 10
__________3 · 2 · 1
= 220.
There is only 1 way to choose all 3 green balloons.
P(3 green balloons) = 1____220
10. Area of large circle is At = π (6)2 = 36π
Area of middle circle is Am = π (4)2 = 16π
Area of small circle is Au = π (2)2 = 4π
Shaded area is As = 16π - 4π = 12π
As___At
= 12π
____36π
= 1__3
The probability that a point is in the shaded area
is 1__3
.
11.Au___At
= 4π
____36π
= 1__9
The probability that a point is in the smallest
circle is 1__9
.
12. P (red) = 5___
20= 1__
4
13. P (red or blue) = 5 + 7_____
20=
3__5
PRACTICE AND PROBLEM SOLVING
14. There are 15 possible outcomes, and 5 outcomes of
a white marble.
P(white marble) = 5___
15= 1__
3
15. There are 15 possible outcomes, and 12 outcomes
of a red or white marble.
P(red or white marble) = 12___15
= 4__5
16. There are 64 possible outcomes.
The number of possible outcomes where both
numbers are greater than 2 is(first number > 2) (second number > 2) = 6 × 6 = 36
P(both numbers greater than 2) = 36___64
= 9___16
.
The probability that both numbers are greater
than 2 is 9___
16.
17. Order is not important. It is a combination.
8 C3 = 8!____
3!5!=
8 · 7 · 6_______3 · 2 · 1
= 56
There is only 1 way to choose the 3 strongest
swimmers.
P(3 strongest swimmers) = 1___56
18. Order is not important. It is a combination.
7 C2 = 7!____2!5!
= 7 · 6____2 · 1
= 21
There is only 1 way to choose books 1 and 2.
P(books 1 and 2) = 1___21
19. 2 ft = 24 in., and 4 ft = 48 in.
Area of platform is At = 24(48) = 1152
Area of hole is As = π (3)2 = 9π
As___At
= 9π
_____1152
= π
____128
≈ 1___42
The probability of the bag landing in the hole is 1___42
.
20. P(red card) = 16___28
= 4__7
The experimental probability that a card is red is 4__7
.
21. never; the theoretical probability of tossing tails on
a fair coin is 1__2
. Tossing the coin 25 times, implies
that tails will appear 12.5 times in order to be equal
to the theoretical probability.
22. P(state that does not border Mississippi)= 1 - P(state that borders Mississippi)
= 1 - 4___49
= 45___49
The probability that the winner will be from a state
that does not border Mississippi is 45___49
.
23a. Area of circle is Ac = π r 2
Area of square is As = (2r)2 = 4 r
2
Ac___As
= π r
2____4 r
2=
π
__4
b. Possible answer: 7852______
10,000≈
π
__4
,
and so, π ≈ 4 × 7852______
10,000≈ 3.141.
24. Possible answer: A roll of a die shows less than 20.
25a. P(made throws 1-25) = 17___25
= 0.68
P(made throws 26-50) = 21___25
= 0.84
P(made throws 51-75) = 19___25
= 0.76
P(made throws 76-100) = 16___25
= 0.64
b. P(throws made) = 73____
100= 0.73
c. The greater the number of experiments, the
closer the experimental probability will be to the
theoretical probability.
26a. P(two 4s) = P(4 and 4) = 1___36
The probability that Mei will have 5 of a kind is 1___36
.
b. P(one 4) = P(4 and not 4) + P(not 4 and 4)
= 5 + 5_____
36=
5___18
The probability that Mei will have 4 of a kind is 5___18
.
c. P(zero 4s) = P(not 4 and not 4) = 25___36
The probability that Mei will have three 4s is 25___36
.
d.1___36
+ 10___36
+ 25___36
= 1
27. Length −−
BD= 4 - 2 = 2; Length
−−
AF= 6 - 1 = 5
Length −−
BD________Length
−−
AF
= 2__5
Probability that a point lies on −−
BD is 2__5
.
28. P(temperature > 90°F in April)
= 5___30
= 1__6
≈ 0.167
409 Holt McDougal Algebra 2
29. June;
P(temperature ≤ 90°F)= 1 - P(temperature > 90°F)
= 1 - 26___30
= 4___30
≈ 0.13
30. it will be slightly greater:
P(temperature ≤ 90°F)= 1 - P(temperature > 90°F)
= 1 - 11___31
= 20___31
≈ 0.645 vs. = 1 - 11___30
= 19___30
≈ 0.633
31. No; yes; a theoretical probability of 1 means all
possible outcomes are favorable outcomes, but a
theoretical probability of 0.99 means there is at least
1 unfavorable outcome.
32. Let r represent the radius of the outer circle.
r = √ ��� x 2 + x
2
r = √ �� 2x2
r = √ � 2x
Aouter = π ( √ � 2x) 2 = 2π x2
Ainner = π x2
Ainner_____Aouter
= π x
2_____2π x
2= 1__
2
The probability that a random point in the large
circle
is within the inner circle is 1__2
.
33.1__2
; each toss is independent.
34. College: female high school players have a better
chance, since 4100_______
456,900>
4500_______549,500
;
pro: male high school players have a better chance,
since 32_______
456,900< 44_______
549,500.
35. Possible answer: Theoretical probability is based on
all possible outcomes, while experimental probability
is based on sample results. The theoretical
probability that a rolled number cube will show a 4
is 1__6
. The experimental probability would be 3___
13 if is
rolled 13 times and shows a 4 three times.
TEST PREP
36. A
P(heads) = 1 - P(tails)
= 1 - 14___25
= 11___25
= 0.44
37. G
Alarge � = 8(16) = 128
Asmall � = 5(14) = 70
Ashaded_______A large �
= 128 - 70________
128
= 58____
128≈ 45%
38. C
2 · 2 · 2 · 2 = 8
39. H
P(sum is 5) = 4___36
= 1__9
40. Length −−
AD= 24 - 4 = 20; Length
−−
BC= 12 - 8 = 4
Length −−
BC________Length
−−
AD
= 4___20
= 1__5
The probability that a point will lie between points
B and C is 1__5
.
CHALLENGE AND EXTEND
41. Possible answer: After a large number of trials,
experimental probability approaches theoretical
probability.
42. There are 24 possible outcomes.
P(no one gets the right trumpet) = 8___
24=
3__8
43. There were 100 experiments.
SPIRAL REVIEW
44. x = - b___2a
= - (-0.85)_______2(0.25)
= 0.85____0.5
= 1.7
f(1.7) = 0.25 (1.7)2 - 0.85(1.7) + 1 = 0.2775
The minimum is 0.2775.
45. x = - b___2a
= - 20_____2(-2)
= 20___4
= 5
f(5) = -2(5)2 + 20(5) - 34 = 16
The maximum is 16.
46. Since the directrix is vertical and to the left of the
vertex, the parabola opens to the right and has the
form x = 1___4p
y 2 , where p > 0.
The distance between the directrix and the vertex
is 3, and so, p = 3, and 4p = 12.
equation: x = 1___12
y2
47. Since the directrix is horizontal and above the
vertex, the parabola opens down and has the
form y = 1___4p
x 2 , where p < 0.
The distance between the directrix and the vertex
is -5, and so, p = -5, and 4p = -20.
equation: y = - 1___20
x2
48a. 11 C5 = 11!_________5!(11 - 5)!
= 11!____5!6!
= 11 · 10 · 9 · 8 · 7
______________ 5 · 4 · 3 · 2 · 1
= 462
She can choose 5 players in 462 ways.
b. 11 P5 = 11!________(11 - 5)!
= 11!___6!
= 11 · 10 · 9 · 8 · 7 = 55,440
She can choose 5 players to play different
positions in 55,440 ways.
410 Holt McDougal Algebra 2
11-3 INDEPENDENT AND DEPENDENT
EVENTS, PAGES 811–818
CHECK IT OUT!
1a. Rolling a 6 once does not affect the probability of rolling a 6 again. The events are independent.P(6 and 6) = P(6) · P(6)
= 1__6· 1__
6= 1___
36
b. Tossing heads once does not affect the probability of tossing heads or tails again. The events are independent.P(H and H and T) = P(H) · P(H) · P(T)
= 1__2· 1__
2· 1__
2= 1__
8
2. The events are dependent because P(red > 4) is different when the sum is 9.
P(red > 4) = 2__6= 1__
3
P(sum > 9 | red > 4) = 5___12
P(sum > 9 AND red > 4)= P(red > 4) · P(sum > 9 | red > 4)
= 1__3· 5___
12= 5___
36; P(sum is 9) changes when it is
known that the red cube is greater than 4.
3a. P(other | Travis) = 5____350
≈ 0.014
b. P(Harris) = 1058_____3125
P(Bush | Harris) = 581_____1058
P(Harris and Bush | Harris) = 1058_____3125
· 581_____1058
≈ 0.186
4a. Replacing the first bead means that the occurrence of the first selection does not affect the probability of the second selection. The events are independent.P(white and red) = P(white) · P(red)
= 15____100
= 3___20
b. Not replacing the first bead means that there will be fewer beads to chose from, affecting the probability of the second selection. The events are dependent.P(white and red) = P(white) · P(red | white)
= 3___10
· 5__9= 1__
6
c. Not replacing the beads means that there will be fewer beads to chose from, affecting the probability of the second and third selections. So the events are dependent.P(not red and not red and not red)= P(not red) · P(not red | not red)· P(not red | not red and not red)
= 5___10
· 4__9· 3__
8= 1___
12
THINK AND DISCUSS
1. Possible answer: a coin landing heads up on one flip and landing heads up on the next flip
2. For independent events A, B, and C,P(A, then B, then C) = P(A) · P(B) · P(C);3 coin flips: P(H, then H, then H)
3.
EXERCISES
GUIDED PRACTICE
1. independent 2. Rolling a 1 once does not affect the probability of
rolling a 1 again. The events are independent.P(1 and 1) = P(1) · P(1)
= 1__6· 1__
6= 1___
36
3. Tossing heads once does not affect the probability of tossing heads again. The events are independent.P(H and H and H) = P(H) · P(H) · P(H)
= 1__2· 1__
2· 1__
2= 1__
8
4. The probability that the product is less than 20
decreases from 7__9
if the blue cube shows a 4.
P(blue 4) = 6___36
= 1__6
P(product < 20 | blue 4) = 4__6= 2__
3P(blue 4 and product < 20)= P(blue 4) · P(product < 20 | blue 4)
= 1__6· 2__
3= 1__
9
5. The probability that the yellow cube shows a
multiple of 3 increases from 1__3
if the product is 6.
P(yellow multiple of 3 | product is 6) = 2__4= 1__
2
6. P(not defective | shipped) = 942____952
= 471____476
7. P(Shipped AND Defective)
= (Defective AND Shipped)
_____________________ Total
= 10_____1000
= 1____100
8. Replacing the first checker means that the occurrence of the first selection does not affect the probability of the second selection. The events are independent.P(black and black) = P(black) · P(black)
= 10___20
· 10___20
= 1__4
411 Holt McDougal Algebra 2
9. Not replacing the first checker means that there will be fewer checkers to choose from, affecting the probability of the second selection, so the events are dependent.P(black and black) = P(black) · P(black | black)
= 10___20
· 9___19
= 9___38
PRACTICE AND PROBLEM SOLVING
10. The choice of activity of the first friend does not affect the probability of the choice of activity of the second friend. The events are independent.The first student will choose one activity. Then, the next student will choose an acitivity. Since there are 4 activities and his friend is in one, the probability of
them being in the same activiity is 1__4
· 1__4
= 1___16
.
11. Rolling an even number does not affect the probability of rolling a 6. The events are independent.P(even and 6) = P(even) · P(6)
= 1__2
· 1__6
= 1___12
12. The probability that the product is greater than 24
P(not employed | not a high school grad) = 0.834_____1.894
P(not a high school grad and not employed)
= 1.894______13.697
· 0.834_____1.894
= 0.834______13.697
= 0.06
17. Not replacing the first slip means that there will be fewer slips to choose from, affecting the probability of the second selection. The events are dependent.P(even and even) = P(even) · P(even | even)
= 4__9
· 3__8
= 1__6
18. Replacing the first slip means that the occurrence of the first selection does not affect the probability of the second selection. The events are independent.P(even and even) = P(even) · P(even)
= 4__9
· 4__9
= 16___81
19. The tossing of heads on a coin does not affect the probability of rolling a 6 on a number cube.
The events are independent.
20. Drawing a 4 and not replacing it affects the probability of drawing an ace.
The events are dependent.
21. Rolling a 1 does not affect the probability of rolling a 4 on the same number cube.
The events are independent.
22. Hitting the bull’s-eye the first time does not affect the probability of hitting the bull’s-eye again.
The events are independent.
23a. P(won | second serve in) = 34___56
≈ 0.61
b. P(double fault | lost) = 3___56
≈ 0.05
24. P(present | present)= 0.9 · 0.95= 0.855
25a. P(not 5 and not 5) = P(not 5) · P(not 5)
= 5__6
· 5__6
= 25___36
P(first reroll no 5s and second reroll no 5s)= P(not 5 and not 5) · P(not 5 and not 5)
= 25___36
· 25___36
= 625_____1296
b. P(5 and 5) = P(5) · P(5)
= 1__6
· 1__6
= 1___36
c. P(5 | 5) = 1__6
26. P(girl) ≈ 147____270
≈ 0.54
27. P(girl | senior) ≈ 71____118
≈ 0.6
28. P(senior | male) ≈ 47____123
≈ 0.38
412 Holt McDougal Algebra 2
29. P(yellow and “Happy Birthday!”)= P(yellow) · P(“Happy Birthday!”)
= 80____100
· 50____100
= 40____100
There are 40 yellow balloons marked “Happy Birthday!” in the box.
30a.Scheduled Flights (thousands)
January to July
2003 2004 2005 Total
On Time 3102 3197 3237 9536
Delayed 598 846 877 2321
Canceled 61 68 82 211
Total 3761 4111 4169 12,068
b. P(canceled | 2004) = 68____4111
≈ 0.017
c. P(2005 | on time) = 3237_____9536
≈ 0.339
31. The events are not dependent. If the coin is fair, P(H) = P(T) = 0.5 for any toss.
TEST PREP
32. A. It cannot be Saturday again next year.
33. F 6 · P(doubles and doubles and doubles)= P(doubles) · P(doubles) · P(doubles)
= 1__6
· 1__6
· 1__6
= 1____216
P(three 5’s in a row)= P(five) · P(five) · P(five)
= ( 1__6
· 1__6
· 1__6) = 1____
216
34a. P(D | A) = 0.2; P(D | B) = 0.2; P(D | C) = 0.2
b. Independent; P(D) and P(E) do not change regardless of whether A, B, or C occurs first.
c. Possible answer: A ball has a 0. − 3 probability of
rolling into pipe A, B, or C. From any pipe, the probability of rolling to location D is 0.2 and to location E is 0.8.
CHALLENGE AND EXTEND
35. 7; P(sum of 7) = 6___36
= 1__6
;
after a roll, P(sum of 7 | 1st roll = 1, 2, 3, 4, 5, 6) = 1__6
.
36a. Let x represent the size of the smallest group. To find the probability that 2 people share a birthday, subtract the complement from 1.1__2
≤ P(2 people share a birthday)
1__2
≤ 1 - P(no one shares a birthday)
1__2
≤ 1 - 365____365
· 364____365
· … · 365 - x_______365
1__2
≤ 1 - ( 1____365)
x
( 365!_________(365 - x)!)
From trial and error, x = 23.
b. The probability of a person not having a birthday
on February 29, in a four-year span, is 1460_____1461
.
Since the probability of one person’s birthday does not affect the probability of the next person’s birthday, the events are independent.
P(no one born on February 29) = ( 1460_____1461)
150 ≈ 0.9
c. Let x represent the size of the smallest group of people.1__2
≤ P(1 person born on February 29)
1__2
≤ 1 - P(no one born on February 29)
1__2
≤ 1 - ( 1460_____1461)
x
1__2
≤ ( 1460_____1461)
x
x ≥ 1012.34 The smallest group is 1013 people.
37. P(lower | woman) = 1 - P(upper | woman)
= 1 - 35___90
= 11___18
;
no, P(lower) ≠ P(lower | woman)
38a. Per 10,000 People Tested
Have
Strep
Do Not
Have StrepTotal
Test Positive 198 98 296
Test Negative 2 9702 9704
Total 200 9800 10,000
b. P(have strep | test positive) = 198____296
= 99____148
SPIRAL REVIEW
39a. p(d) = 18.3g; p(j) = 32.5g
b.
c. vertical stretch by a factor of ≈ 1.78
40. The graph of the first equation is a hyperbola. The graph of the second equation is a line. There may be as many as two points of intersection.
Solve each equation for y.
y = ± √ 1__2
x2 - 3
y = 2 The points of intersection are when x ≈ ±3.7 and y = 2.
413 Holt McDougal Algebra 2
41. The graph of both equations is a hyperbola. There
may be as many as four points of intersection.
Solve each equation for y.
y = ± √ ���� 2x2 - 9
y = ± √ ���� 1__6
x2 + 11___
3 The points of intersection
are when
x ≈ ± 2.6 and y ≈ ± 2.2.
42. The graph of the first equation is a circle. The graph
of the second equation is a parabola. There may be
as many as two points of intersection.
Solve each equation for y.
y = ± √ ���� 16 - x2
y = - 3__2
- 5__2
x2
The points of intersection
are when
x ≈ ±1.0 and y ≈ -3.9.
43. P(sum is 12) = 1___36
44. P(sum < 5) = 6___36
= 1__6
45. P(at least one is odd)= 1 - P(even and even)
= 1 - 3__6
· 3__6
= 1 - 1__4
= 3__4
46. P(at least one < 3)= 1 - P(both ≥ 3)
= 1 - 4__6
· 4__6
= 1 - 4__9
= 5__9
11-4 COMPOUND EVENTS,
PAGES 819–825
CHECK IT OUT!
1a. Each student can only vote once.
b. P(votes for Kline � voted for Vila)= P(votes for Kline) + P(voted for Vila)= 20% + 55% = 75%
P(B � (A � C))= P(B) + P(A � C) - P(B � (A � C))= 0.3 + 0.9 - 1 = 0.2
SPIRAL REVIEW
42. The data can be modeled by
y = 0.5 x3 + 1.5 x
2 - 3x - 4.
43. The data can be modeled by
y = -1.5x3 - 6 x
2 + 16.5x + 45.
44. The function is composed of a constant piece and a
linear piece. The domain is divided at x = -1.
x f(x) = 2 f(x) = 2x + 4
-2 2 0
-1 2 2
0 2 4
No circle is required at (-1, 2) because the function
is connected at that point.
416 Holt McDougal Algebra 2
45. The function is composed of two parabolas. The domain is divided at x = 1.
x f(x) = 1 - x2
f(x) = x2 - 1
0 1 -1
1 0 0
2 -3 3
No circle is required at (0, 0) because the function is connected at that point.
46. P(heads and heads)= P(heads) · P(heads)
= 1__2
· 1__2
= 1__4
47. P(heads and heads and tails and tails)= P(heads) · P(heads) · P(tails) · P(tails)
= 1__2
· 1__2
· 1__2
· 1__2
= 1___16
48. P(sum > 10 and first cube is a 6)= P(sum > 10) · P(first cube is a 6 | sum > 10)
= 3___36
· 2__3
= 1___18
READY TO GO ON? PAGE 827
1. 10 P5 = 10!________(10 - 5)!
= 10!___5!
= 10 · 9 · 8 · 7 · 6= 30,240
2. 8 C4 = 8!________4!(8 - 4)!
= 8!____4!4!
= 8 · 7 · 6 · 5 __________ 4 · 3 · 2 · 1
= 70
3. 6 P5 = 6!_______(6 - 5)!
= 6!__1!
= 6 · 5 · 4 · 3 · 2= 720
4. P(iced tea) = 3___18
= 1__6
5. P(out of ink and out of ink)= P(out of ink) · P(out of ink | out of ink)
= 2__9
· 1__8
= 1___36
6. Area of large triangle is At = 1__2
(15)(4) = 30
Area of shaded region is As = 1__2
(4)(4) = 8
As___At
= 8___30
= 4___15
The probability that the point is in the shaded
region is 4___15
.
7. P(not rolling a 2) = 1 - P(rolling a 2)
= 1 - 12___50
= 19___25
8. The result of a toss does not affect the probability of the next toss.P(tails and tails and tails and tails and heads)= P(tails) · P(tails) · P(tails) · P(tails) · P(heads)
= 1__2
· 1__2
· 1__2
· 1__2
· 1__2
= 1___32
9. P(sum ≥ 10) changes after a red 6 has occurred.
P(sum ≥ 10 and red 6)
P(sum ≥ 10) = 1__6
P(red 6 | sum ≥ 10) = 1__2
10. P(11th grade | geometry) = 33____127
11. Not replacing the red checker after it is selected affects the probability of the next selection. The events are dependent.P(red and black)= P(red) · P(black | red)
= 15___25
· 10___24
= 1__4
12. P(even � 1)
= P(even) + P(1)
= 15___30
+ 1___30
= 8___15
13. P(even � multiple of 7)= P(even) + P(multiple of 7)
- P(even � multiple of 7)
= 15___30
+ 4___30
- 2___30
= 17___30
14. 85 - 60 = 25 part-time employees. 85 - 40 = 45 not married employees.P(part time � not married) = 1 - P(full time � married)
= 1 - P(full time) + P(married)
- P(full time � married)
= 1 -
60___85
+ 40___85
- 30___85
�
= 15___
85P(part time � not married)= P(part time) + P(not married)
minimum: 11 first quartile: 13 maximum: 23 third quartile: 18 median: 14 IQR: 5
4. − x = 14___10
= 1.4
0 3 1 1 0
x - − x -1.4 1.6 -0.4 -0.4 -1.4
(x - − x)
2 1.96 2.56 0.16 0.16 1.96
5 1 0 3 0
x - − x 3.6 -0.4 -1.4 1.6 -1.4
(x - − x)
2 12.96 0.16 1.96 2.56 1.96
σ 2 = 26.4____
10= 2.64; σ = √ �� 2.64 ≈ 1.6
5. The mean is about 5.4 and the standard deviation is about 4.5.
Two standard deviations is about 2(4.5) = 9. Values 9 units below the mean are negative and would not make sense in this problem. Values greater than 9 units away from the mean are outliers. So, 19, the number of scored runs, is an outlier.
The mean increases from ≈ 4.3 to ≈ 5.4, and the standard deviation increases from ≈ 2.3 to ≈ 4.5.
THINK AND DISCUSS
1. Possible answer: The mean increases by the constant.
2. Possible answer: The standard deviation is unchanged.
3. Possible answer: The standard deviation is multiplied by √ � 2.
8. 22, 27, 31, 33, 34 minimum: 22 first quartile: 24.5 maximum: 34 third quartile: 33.5 median: 31 IQR: 9
9. − x = 20___5
= 4
3 3 4 5 5
x - − x -1 -1 0 1 1
(x - − x)
2 1 1 0 1 1
σ 2 = 4__
5= 0.8 σ = √ �� 0.8 = 0.89
10. − x = 112____7
= 16
10 12 14 15 18 20 23
x - − x -6 -4 -2 -1 2 4 7
(x - − x)
2 36 16 4 1 4 16 49
σ 2 = 126____
7= 18 σ = √ �� 18 = 4.24
418 Holt McDougal Algebra 2
11. − x = 147____6
= 24.5
7 14 21 28 35 42
x - − x -17.5 -10.5 -3.5 3.5 10.5 17.5
(x - − x)
2 306.25 110.25 12.25 12.25 110.25 306.25
σ 2 = 857.5_____
6= 142.92 σ = √ ��� 142.92 = 11.95
12. The mean is 46. −
6 and the standard deviation is about 8.4.
Three standard deviations is about 3(8.4) = 25.2. Values greater than 25.2 units away from the mean are outliers. So 19, the width of the desk, is an outlier.
The mean decreases from ≈ 49.2 to 46. −
6 , and the standard deviation increases from ≈ 0.72 to ≈ 8.4.
19. 1, 2, 3, 3, 4 minimum: 1 first quartile: 1.5 maximum: 4 third quartile: 3.5 median: 3 IQR: 2
20. − x = 21___5
= 4.2
4 4 4 4 5
x - − x -0.2 -0.2 -0.2 -0.2 0.8
(x - − x)
2 0.04 0.04 0.04 0.04 0.64
σ 2 = 0.8___
5= 0.16 σ = √ �� 0.16 = 0.4
21. − x = 245____7
= 35
8 12 30 35 48 50 62
x - − x -27 -23 -5 0 13 15 27
(x - − x)
2 729 529 25 0 169 225 729
σ 2 = 2406_____
7≈ 343.71 σ = √ ��� 343.71 ≈ 18.54
22. − x = 132____4
= 33
14 26 40 52
x - − x -19 -7 7 19
(x - − x)
2 361 49 49 361
σ 2 = 820____
4= 205 σ = √ �� 205 ≈ 14.32
23. The mean is about 22.8 and the standard deviation is about 11.5.
Three standard deviations is about 3(11.5) = 34.5. Values greater than 34.5 units away from the mean are outliers. So, 58 is an outlier.
The mean increases from ≈ 19.8 to ≈ 22.8, and the standard deviation increases from ≈ 5.6 to ≈ 11.5.
24. Possible answer: {3, 3, 9, 9}
25. The mean; 37° is an outlier and affects the mean greatly.
26. 25; Q3 + 1.5 (IQR) = 5 + 1.5(2)= 8;
25 > 8
27. 15; Q1 - 1.5 (IQR) = 79 - 1.5(11)= 62.5;
15 < 62.5
28. 92 and 1; Q 3 + 1.5 (IQR)= 36 + 1.5(3) = 40.5
92 > 40.5
Q1 - 1.5 (IQR)= 33 - 1.5(3) = 28.5
1 < 28.5
29. The time intervals in which the duration time is an outlier are three times the standard deviation away from the mean, < 0.3 min or > 6.9 min. There are no outliers for duration times.
30. The intervals in which the time between eruptions is an outlier are three times the standard deviation away from the mean, < 32.6 min or > 109.4 min. There are no outliers for time between eruptions.
31. Ruth; possible answer: 13
32. Ruth; possible answer: 6
33. Possible answer: Ruth: 36; Aaron: 18
34. Aaron; Ruth’s data are more spread out, and the set’s IQR is twice the IQR for Aaron’s set.
35. expected value = 500(0.001) - 1(0.999) = -0.499 The expected gain is -$0.499.
419 Holt McDougal Algebra 2
36. expected value = 100(0.10) - 2(0.30) + 0(0.60) = 9.40 The expected value is $9.40.
37. B; the student should have squared the differences.
38. Sometimes; possible answer: when 2 coins are tossed, the expected number of heads is 1, a possible outcome. When 3 coins are tossed, the expected number, 1.5, is not a possible outcome.