Question

If the average (arithmetic mean) of the four numbers $3,15,32$ and $(N+1)$ is $18$, then $N=$

• A. $19$
• B. $20$
• C. $21$
• D. $22$
• E. $29$

Answer 1

Answer: (C)

$21$

Mean is the sum of the values divided by the total number of values in the data set.

Given data set is $3,15,32,(N+1)$
Total number of values is $4$

Given that arithmetic mean is $18$

$⟹\frac{3+15+32+N+1}{4}=18$

$⟹3+15+32+N+1=18\times 4$

$⟹51+N=72$

$⟹N=72-51=21$