Question 30

The mean of 21 observations (all different) is 40. If each observation greater than the median is increased by 21, then the mean of observations will become:

Solution

Given that the mean of 21 observations is 40. So total sum = 21 x 40 = 840

The median of the number = (n+1)/2 = 22/2 = 11th number

Given that the observations greater than median i.e 11th number is increased by 21. There are 10 observations like that.

Total sum becomes 840 + 210 = 1050

The new mean will be 1050/21 = 50

Hence, option A is the correct answer.

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