1. The marks obtained by 10 students in a mathematics test are 75, 90, 70, 50, 70, 50, 75, 90, 70 and 75. Find their median mark?
a. 70
b. 72.5
c. 75
d. 71.5
2. The numbers 2, 3, 4, 4, 2x + 1, 7, 7, 8 and 9 are written in an ascending order. If the median is 7, then find mode of this data?
a. 8
b. 7
c. 4
d. 9
3. The mean of six numbers is 23. If one of the numbers is excluded, the mean of the remaining numbers becomes 20. The excluded number is
a. 36
b. 38
c. 37
d. 39
4. The mean of five observations is 15. If the mean of first three observations is 14 and that of last three is 17, then find the third observation?
a. 29
b. 31
c. 18
d. 32
5. The mean of 50 observations is 39. If one of the observations which was 23 was replaced by 43, what will be the resulting mean?
a. 38.4
b. 39.4
c. 39
d. 40.3
6. The traffic police recorded the speed (in km/h) of 10 motorists as 48, 52, 57, 55, 42, 39, 60, 49, 53 and 47. Later an error in recording instrument was found. If the instrument has recorded the speed 5 km/h less in each case, then find the correct average speed of the motorists?
a. 54.5 km/h
b. 52.5 km/h
c. 55.2 km/h
d. 50.2 km/h
7. When the data consists of 3, 4, 5, 4, 3, 4, 5, which statement is true?
a. Mean > mode
b. Mean = mode
c. Mean > median
d. Median < mode
8. The difference between the mean and median of first five prime numbers is
a. 0.8
b. 0.6
c. 0.4
d. 1
9. Vihaan has marks of 92, 85, and 78 in three mathematics tests. In order to have an average of exactly 87 for the four math tests, what marks he should obtain?
a. 92 marks
b. 93 marks
c. 91 marks
d. 90 marks
10. If the mean of the observations: x, x + 3, x + 5, x + 7, x + 10 is 9, the mean of last three observations is
a. 7
b. 9
c.
d.

Chapter - 14 Statistics Quiz-3 | Math Class 9th

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