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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