Mathematics - Probability Question with Solution | TestHub

MathematicsProbabilityGeneral (Event SS, Definitions, Odd against/Favour)Medium2 minPYQ_2025

MathematicsMediumsingle choice

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

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Answer:

Solution:

$x P (x) x = 0 \frac{^{7} C _{2}}{^{10} C _{2}} x = 1 \frac{^{7} C _{1}^{3} C _{1}}{^{10} C _{2}} x = 2^{3}^{10} C_{2}$
$μ = Σ x_{i} P (x_{i}) = 0 + \frac{7}{15} + \frac{2}{15} = \frac{3}{5} Variance (x) = Σ P_{i} (x_{i} - μ)^{2} = \frac{28}{75}$

Stream:JEESubject:MathematicsTopic:ProbabilitySubtopic:General (Event SS, Definitions, Odd against/Favour)

⏱ 2mℹ️ Source: PYQ_2025

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