Question

[dummy - to replace with video] The weights of five girls in a class are 45 kg, 55 kg, 42 kg, 50 kg and 56 kg. Find the mean deviation about mean using the assumed mean method.

• A. 3.84
• B. 4.88
• C. 5.21
• D. 6.04

Answer 1

The correct option is B 4.88

$Mean,\overline{x}=\frac{45+55+42+50+56}{5}=49.6kg$

Deviations from mean are tabulated below.
Let the assumed mean be 50
$\begin{array}{cc}X& D=|X-A|\\ 45& 5\\ 55& 5\\ 42& 8\\ 50& 0\\ 56& 6\\ & \sum D=24\end{array}$

$M.D\left(\overline{x}\right)=\frac{\sum D+(\overline{x}-A)(\sum f_B-\sum f_A)}{N}=\frac{24+(49.6-50)(2-3)}{5}=\frac{24.4}{5}=4.88$