Question

The mean of $100$ observations is $50$. If one of the observations which was $50$ is replaced by$150$, the resulting mean will be :

• A. $50.5$
• B. $51$
• C. $51.5$
• D. $52$

Answer 1

Answer: (B)

$51$

Mean of $100$ terms = $50$
Sum of $100$ terms = $50\times 100$ = 5000
After replacing a term by $150$, sum = $5000-50+150=5100$
Mean = $\frac{5100}{100}=51$