The average height of 30 boys out of a class of 50 is 160 cm. If the average height of the remaining boys is 165 cm, the average height of the whole class (in cm) is :

A. 161

B. 162

C. 163

D. 164

Answer: Option B

Solution(By Examveda Team)

Average height of the whole class
$$\eqalign{ & = \frac{{30 \times 160 + 20 \times 165}}{{50}} \cr & = \frac{{3 \times 160 + 2 \times 165}}{5} \cr} $$
= 96 + 66
= 162 cm