Question

A student obtained the following marks percentage in an examination:
English - $50$, Accounts - $75$, Economics - $60$, B.Std. -$80$, Hindi - $55$.
If weights are $2,3,3,2,1$ respectively allotted to the subjects, his weighted mean is

• A. $\frac{50+75+60+80+55}{2+3+3+2+1}$
• B. $\frac{(50\times 2)+(75\times 3)+(60\times 3)+(80\times 2)+(55\times 1)}{5}$
• C. $\frac{50\times 2+75\times 3+60\times 3+80\times 2+55\times 1}{2+3+3+2+1}$
• D. none

Answer 1

Answer: (C)

$\frac{50\times 2+75\times 3+60\times 3+80\times 2+55\times 1}{2+3+3+2+1}$

Let the weighted mean be $M$ and

$f=\{50,75,60,80,55\}$, $x=\{2,3,3,2,1\}$

$M=\frac{\sum fx}{\sum f}$

$M=\frac{50\times 2+75\times 3+60\times 3+80\times 2+55\times 1}{2+3+3+2+1}$

Hence, this is the required answer.