Question

State true or false:

The mean of $100$ observations is $40$. It is found that an observation $53$ was misread as $83$. The correct mean 39.7

• A. False
• B. True
• C. Can't determine
• D. None of these

Answer 1

Answer: (B)

True

Mean of $100$ observations = $40$
Sum of $100$ observations = $40\times 100$ = $4000$
After replacing the misread observation $83$ to $53$,
Sum of $100$ observations = $4000-83+53$ = $3970$
New mean = $\frac{3970}{1000}$ = $39.70$