Question

The average marks of three batches of students having 70, 50 and 30 students respectively are 50, 55 and 45. Find the average marks of all the 150 students, taken together.

• A. $50.67$
• B. $40.67$
• C. $50.60$
• D. $40.60$

Answer 1

Answer: (A)

$50.67$

Given that, the average marks of 70, 50 and 30 students respectively are 50, 55 and 45 marks.

$\therefore$ the total marks of 70, 50 and 30 students will be,

$70\times 50,50\times 55$ and $30\times 45$ respectively.

The average marks of all the 150 students will be:

$=\frac{(3500+2750+1350)}{(70+50+30)}$ $[\text{Average}=\frac{\text{Sum of all quantities}}{\text{Number of quantities}}]$

$\Rightarrow \frac{7,600}{150}$

$\Rightarrow 50.67$

Hence, the average marks of all the 150 students, taken together are $50.67$