JEE Mains · Maths · STD 12 - 13. probability
A box contains 10 pens of which 3 are defective. A sample of 2 pens is drawn at random and let \(X\) denote the number of defective pens. Then the variance of X is
- A \(\frac{11}{15}\)
- B \(\frac{28}{75}\)
- C \(\frac{2}{15}\)
- D \(\frac{3}{5}\)
Answer & Solution
Correct Answer
(B) \(\frac{28}{75}\)
Step-by-step Solution
Detailed explanation
\(\begin{array}{|r|c|c|c|}\hline x & \mathrm{x}=0 & \mathrm{x}=1 & \mathrm{x}=2 \\\hline \mathrm{P}(\mathrm{x}) & \frac{{ }^7 \mathrm{C}_2}{{ }^{10} \mathrm{C}_2} & \frac{{ }^7 \mathrm{C}_1^3 \mathrm{C}_1}{{ }^{10} \mathrm{C}_2} & { }^3{ }^{10} \mathrm{C}_2 \\\hline\end{array}\)…
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