Question 59

The mean of 100 items is 51. It was discovered that three items, which should have been 50, 70, 60, were wrongly read as 40, 20, 50, respectively. The correct mean is:

Solution

Given,

Mean of 100 items = 51

Sum of 100 items = $$51\times100=5100$$

Sum of the items added = 50 + 70 + 60 = 180

Sum of the items replaced = 40 + 20 + 50 = 110

New sum = 5100 - 110 + 180 = 5170

$$\therefore\ New\ mean\ =\ \frac{5170}{100}=51.7$$

Hence, Option B is correct.

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