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Question: Answered & Verified by Expert
An analysis of monthly wages paid to the workers in two firms A and B belonging to the same industry the following result:
\begin{array}{|l|c|c|}
\hline & Firm A & Firm B \\
\hline Number of workers & 500 & 600 \\
\hline Average monthly wage & ₹ 1860 & ₹ 1750 \\
\hline Variance of distribution of wages & 81 & 100 \\
\hline
\end{array}
The average of monthly wages and variance of distribution of wages of all the workers in the firms A and B taken together are
MathematicsStatisticsNDANDA 2018 (Phase 2)
Options:
  • A $₹ 1860,100$
  • B $₹ 1750,100$
  • C $₹ 1800 \mathrm{~m}, 81$
  • D None of above
Solution:
2702 Upvotes Verified Answer
The correct answer is: None of above
Combined Average $=\frac{500 \times 1860+600 \times 1750}{1100}=1800$
Combined Variance
$$
\begin{array}{l}
=\frac{500(81+3600)+600(100+2500)}{1100} \\
=\frac{(5 \times 3681)+(6 \times 2600)}{1100} \approx 3092
\end{array}
$$

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