IMO Practice Test: Measures of Central Tendency | Class 8 Mathematics

Question 1 of 6

The mean of 10 numbers is 20. If each number is multiplied by 3, what is the new mean?

20

40

60

80

Explanation: If each value is multiplied by k, mean multiplies by k: 20×3=60

Question 2 of 6

The median of 7, 8, 12, x, 15, 18, 20 is 14. Find x.

13

14

15

16

Explanation: Sorted order: 7,8,12,x,15,18,20; median is 4th value=x=14

Question 3 of 6

The mean of 11 observations is 50. If the mean of first 6 is 45 and last 6 is 55, find the 6th observation.

40

45

50

55

Explanation: Sum of all=550; sum first6=270; sum last6=330; 6th counted twice: 270+330-550=50

Question 4 of 6

Find the mode of: 2, 2, 3, 3, 4, 4, 5, 5

2

3

4

No mode

Explanation: All values appear exactly twice → no mode

Question 5 of 6

The mean of 6 numbers is 8. One number is removed and the mean becomes 7. Find the removed number.

10

12

13

14

Explanation: Sum of 6=48; sum of 5=35; removed=48-35=13

Question 6 of 6

In a class test, the mean score of 30 students is 75. Later, it was found that one score 85 was recorded as 58. Find the correct mean.

75.9

76.5

77.1

78.0

Explanation: Sum incorrect=2250; correct sum=2250-58+85=2277; correct mean=2277/30=75.9

IMO Practice Test — Measures of Central Tendency