Answer to Question #202340 in Statistics and Probability for Aasia Tariq

Question

a.  A batch of50 parts contains six defects. If two parts are drawn randomly one at a time without replacement, what is the probability that both parts are defective?

b. If this experiment is repeated, with replacement, what is the probability that both parts are defective?

Answer 1

a.

$$P(DD)=\dfrac{6}{50}\cdot\dfrac{6-1}{50-1}=\dfrac{3}{245}$$

b.

$$P(DD)=\dfrac{6}{50}\cdot\dfrac{6}{50}=\dfrac{9}{625}$$