If the average weight of 6 students is 50 kg. If two student of average weight of 51 kg are added and two other students of average weight of 55 kg are also added then the average weight of all the students is :

A. 61 kg B. 51.5 kg C. 52 kg D. 51.2 kg Answer: Option D

Solution(By Apex Team)

$\begin{array}{l}\text{According to the question,}\\ \text{ Required Average }\\ =\Large\frac{6\times50+51\times2+55\times2}{10}\\ =\Large\frac{300+212}{10}\\ =\Large\frac{512}{10}\\ =51.2\mathrm{Kg}\end{array}$

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