Question

When tested, the lives (in hours) of 5 bulbs were noted as follows: $1357,1090,1666,1494,1623$. The mean deviations (in hours) from their mean is

• A. 178
• B. 220
• C. 179
• D. 356

Answer 1

The correct option is A 178

The lives of 5 bulbs are: $1357,1090,1666,1494,1623$

Mean$=\frac{1357+1090+1666+1494+1623}{5}$

Mean $=\frac{7230}{5}$

Mean = 1446

$\begin{array}{cc}{x}_i& d_i=|x_i-\overline{x}|\\ 1357& 89\\ 1090& 356\\ 1666& 220\\ 1494& 48\\ 1623& 177\\ Total& \sum d_i=890\end{array}$

MD$=\frac{\sum d_i}{n}=\frac{890}{5}=178$

Hence, mean deviation from the mean is 178 hours.

Hence, Option (𝐴) is correct.