### The average of 6 observations is 45.5. If one new observation is added to the previous observations, then the new average becomes 47. The new observation is :

A. 58 B. 56 C. 50 D. 46 Answer: Option B

### Solution(By Apex Team)

$\begin{array}{l}\text{Let the new observation be = x}\\ \text{According to the question,}\\ \text{6 × 45.5 + x = 7 × 47}\\ \text{273.0 + x = 329}\\ \text{x = 329 – 273}\\ \text{x = 56}\end{array}$

A. 20
B. 21
C. 28
D. 32

A. 18
B. 20
C. 24
D. 30

A. 10 years
B. 10.5 years
C. 11 years
D. 12 years