In computing the mean of 8 numbers, a boy mistakenly used 17 instead of 25…

In computing the mean of 8 numbers, a boy mistakenly used 17 instead of 25 as one of the numbers and obtained 20 as the mean. Find the correct mean

Correct Answer: Option B

Explanation

(Mean = frac{sum of items}{total number of items})

(20 = frac{x}{8} implies x = 160)

The sum of the 7 nos = 160 – 17 = 143

Correct mean = (frac{143 + 25}{8} = frac{168}{8} = 21)