Question

The mean of $100$ items is $49$ . It was later discovered that three items taken as $40,20,50$ were actually $60,70,80$ respectively. The correct mean is:

• A. $48$
• B. $50$
• C. $82.5$
• D. $41.5$

Answer 1

Answer: (B)

$50$

Mean of 100 items $=49$

sum of 100 items = $49\times 100=4900$

Correct sum $=4900-40-20-50+60+70+80$

$=4900+70+30$

$=4900+100$

$=5000$

Correct mean = $\frac{5000}{100}=50$