Question

The mean of 100 items was found to be 30. If at the time of calculation, two items were wrongly taken as 32 and 12 instead of 23 and 11, then the correct mean is -

• A.
  29.8
• B.
  28.8
• C.
  29.9
• D.
  28.9

Answer 1

The correct option is C

29.9
$\overline{x}=30\Rightarrow \frac{S_{100}}{100}=30\Rightarrow S_{100}=3000\text{Correct sum}=S_{100}-32-12+23+11=3000-10=2990\text{Correct mean}=\frac{2990}{100}=29.9$