Independent solution

How to solve this Hypergeometric Distribution question

Setup

Setup

The finite box contains eight good items and two defective items, and three are sampled without replacement.

G=8,D=2,n=3G=8,\qquad D=2,\qquad n=3

Model

Model

Acceptance occurs for exactly two good items or exactly three good items.

Pr(accept)=(82)(21)+(83)(20)(103)\Pr(\text{accept})=\frac{\binom82\binom21+\binom83\binom20}{\binom{10}{3}}

Compute

Compute

Evaluate the two disjoint composition counts.

(82)(21)=56,(83)(20)=56\binom82\binom21=56,\qquad \binom83\binom20=56
Pr(accept)=112120=1415=0.9333333333\Pr(\text{accept})=\frac{112}{120}=\frac{14}{15}=0.9333333333

Answer

Answer

The acceptance probability rounds to 0.93.

0.93(E)\boxed{0.93\quad\text{(E)}}