Q266 / 270 · NDA 2018 (Phase 2) · Mathematics
An analysis of monthly wages paid to the workers in two firms A and B belonging to the same industry the following result:
The average of monthly wages and variance of distribution of wages of all the workers in the firms A and B taken together are
The average of monthly wages and variance of distribution of wages of all the workers in the firms A and B taken together are
- A₹ 1860,100
- B₹ 1750,100
- C₹ $1800 \mathrm{~m}, 81$
- Correct answerDNone of above
Solution
Combined Average
$=\frac{500 \times 1860+600 \times 1750}{1100}=1800$
Combined Variance
$\begin{aligned}
& =\frac{500(81+3600)+600(100+2500)}{1100} \\
& =\frac{(5 \times 3681)+(6 \times 2600)}{1100} \approx 3092
\end{aligned}$
Hence, the correct answer is option: 'D'.