Question 62

The mean of 100 items is 47.It was discovered that three items which should have been 60, 70, 80 were wrongly read as 40, 20, 50, respectively. The correct mean is:

Solution

Given,

Mean of 100 items = 47

Sum of observation = $$mean\times\ number\ of\ observation$$

i.e; $$47\times\ 100\ =\ 4700$$

Correct sum = 4700 + (60 + 70 + 80) - (40 + 20 + 50)

i.e; 4800

Correct mean = $$\frac{Correct\ sum}{number\ of\ observation}$$

i.e $$\frac{4800}{100}=\ 48$$

Hence, Option A is correct

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