Question

The mean of 100 items was found to be 64. Later on, it was discovered that two items were misread as 26 and 9 instead of 36 and 90 respectively. The correct mean is

• A. 64.86
• B. 65.31
• C. 64.91
• D. 64.61

Answer 1

The correct option is C

64.91

Mean of 100 items is 64

$\Rightarrow \frac{total}{100}=64\Rightarrow total=6400$

36 and 90 were misread as 26 and 9

Hence, difference in values is, $(36-26)+(90-9)=10+81=91$

The misread values are less than the actual values, hence the new total is 6400 + 91 = 6491

New mean $=\frac{6491}{100}=64.91$