Exercises on Measures of Central Tendency Ente r
There are seven multiple-choice questions in this exercise. Click the letter to select the corresponding answer.
Enter
1. This is the frequency distribution of the ages of students in a class.
Age Frequency
11 7
12 19
13 10
14 4
Find out their mean age.
A
B
C
12
12.3
12.5
D 19
12 is the mode, not the mean. Try again!
Hints:
Return
Age Frequency
11 7
12 19
13 10
14 4
Mean age40
4141013912711
Sorry! You forgot to count the frequencies! Try again!Hints:
Return
Age Frequency
11 712 1913 1014 4
Mean4
114113112111
5.12
Age Frequency
11 112 113 114 1
Mean age = ?
19 is the frequency of 12 year-old. That means there are 19 students who are 12 years old. You should be looking for the mean of the students’ age. Try again!
Hints:
Return
Age Frequency
11 7
12 19
13 10
14 4
Mean age40
4141013912711
2. This is the frequency distribution of the weights of 50 members of a children’s choir.
Weight( kg) Class mark, x kg Frequency
36-40 38 241-45 43 846-50 48 1151-55 53 1256-60 58 1361-65 63 4
A
B
C
51.8 kg
56-60 kg
50.5 kg
Find out their mean weight.
56-60 kg is the modal class, not the mean weight. Try again! Hints:
Mean weight
Return
Weight( kg) Class mark, x kg Frequency
36-40 38 241-45 43 846-50 48 1151-55 53 1256-60 58 1361-65 63 4
50
463135812531148843238
Sorry! You forgot to count the frequencies. Try again! Hints:
Return
Mean weightWeight Frequency
1x2x3x
4x
1f
2f
3f
4f4321
44332211
ffff
fxfxfxfx
Weight( kg) Class mark, x kg Frequency
36-40 38 241-45 43 846-50 48 1151-55 53 1256-60 58 1361-65 63 4
Mean weight= ?
3. The table shows the number of mobile phones owned by 100 families.
Number of mobile phones Frequency
2 23 64 385 166 207 18
Find the mode.
A
B
C
4
4.5
5
D 38
5 is the mean of mobile phones owned by each family, not the mode.
Hints:
Mode is the most frequent datum/data in a set of data.
Return
Try again!
Hints: Mode is the most frequent datum/data in a set of data.
Return
38 is the frequency of 4. That means there are 38 families that have 4 mobile phones. You should be looking for the mode!
Try again!
Sorry, your answer is wrong. Try again!
Hints: Mode is the most frequent data in a set of data.
Return
4. This is the frequency distribution of the time spent by Kelly on waiting for the bus last week.
Time (minutes) Class mark (minutes) Frequency (days)
1-5 3 06-10 8 1511-15 13 1216-20 18 1221-25 23 1
Find the modal class.A
C
D
12.9 minutes
11-15 and 16-20 minutes
6-10 minutes
B 8 minutes
Bingo !Modal class is the most frequent class in a set of data. Therefore:
Modal class = 6-10 minutes
Next question
12.9 is the mean of the time spent on waiting for the bus, not the modal class.
Hints: Modal class is the most frequent class in a set of data.
Return
Try again!
8 is the class mark of the class “6-10 minutes”. You should be looking for the modal class of the time spent by Kelly on waiting for the bus in the past 40 days.
Hints: Modal class is the most frequent class in a set of data.
Return
Try again!
Sorry, your answer is wrong. Try again! Hints: Modal class is the most frequent class in a set of data.
Return
5. This is the frequency distribution of the time spent by 80 students in finishing a 3,000-meter track.
Time(minutes) Class mark (minutes) Frequency (No. of person)
10-15 13 4
16-20 18 9
21-25 23 14
26-30 28 14
31-35 33 9
Find the modal class.A
B
C
16-20 and 31-35 minutes
21-25 and 26-30 minutes
15.3 minutes
Bingo !Modal class is the most frequent class in a set of data. Therefore:
Modal class = 21-25 and 26-30 minutes
Next question
15.3 minutes is the mean of the time needed to finish a 3,000-meter track, not the modal class!
Hints: Modal class is the most frequent class in a set of data.
Return
Try again!
Sorry, your answer is wrong. Try again!
Hints: Modal class is the most frequent class in a set of data.
Return
2500023000210001900017000150001300011000900070005000
10
20
30
40
50
60
70
80
90
100
0
Salary (dollars)
Cum
ulative frequency (person)
6. This is the cumulative frequency polygon of the salaries of a company’s employees. Find the median.
A
B
C
15000 dollars
15400 dollars
15800 dollars
Bingo !Since there are 90 employees in the company, there median can be found at the 45th employee. Therefore:
Median=15000 dollars
Next question
Sorry, you didn’t pay attention to the cumulative number of employee.
Since there are 90 employees in the company, there median can be found at the 45th employee. Try again!
Hints:
Return
7. This is the cumulative frequency polygon of rainfall in Island West during the past 40 days. Find the median.
B
C
D
70 mm
77 mm
85 mm
Cu
mu
lative freq
uen
cy (day)
020 40 60 80 100 120
5
10
15
20
25
30
35
40
45
Rainfall amount (mm)
A 20 mm
Bingo !The median of rainfall in 40 days can be found at the 20th day. Therefore:
Median = 70 mm
End
Sorry, you didn’t pay attention to the cumulative number of days. Try again!
Hints: The median of rainfall in 40 days can be found at the 20th day.
Return