Question

The average of 100 observations is 50. What will be the difference of the resulting average to original one, when an observation with value of 50 is replaced with 150?

• A. 0.5
• B. 1
• C. 1.5
• D. 2

Answer 1

The correct option is B 1

Average of 100 observations = 50

$⟹$ $\frac{\text{Total}}{100}$ = 50
$⟹$ Total = 5000

50 is replaced by 150, hence the difference between the values
= 150 - 50 = 100

$\therefore$ New total = 5000 + 100 = 5100
New average = $\frac{5100}{100}$ = 51

Difference of averages = 51 - 50 = 1