MCQ 11 Mark
If the mean of a frequency distribution is 8.1 and $\sum f _{ i } x _{ i }=132+5 k , \sum f _{ i }=20$ then k =
- A3
- B4
- C5
- ✓6
Answer
View full question & answer→Correct option: D.
6
(D) 6
Explanation: Mean = 8.1
$\Sigma f _{ i } x _{ i }=132+5 k$
$\sum f_i=20$
$\therefore$ Mean $=\frac{\Sigma f_i x_i}{\Sigma f_i} \Rightarrow 8.1=\frac{132+5 k}{20}$
$\Rightarrow 132+5 k=8.1 \times 20=162$
$\Rightarrow 5 k =162-132=30$
$\Rightarrow k =\frac{30}{5}=6$
Explanation: Mean = 8.1
$\Sigma f _{ i } x _{ i }=132+5 k$
$\sum f_i=20$
$\therefore$ Mean $=\frac{\Sigma f_i x_i}{\Sigma f_i} \Rightarrow 8.1=\frac{132+5 k}{20}$
$\Rightarrow 132+5 k=8.1 \times 20=162$
$\Rightarrow 5 k =162-132=30$
$\Rightarrow k =\frac{30}{5}=6$






