Question

A box in a certain supply room contains six 40-w lightbulbs, four 60-w bulbs, and three 75-w bulbs. suppose that three bulbs are randomly selected. (round your answers to four decimal places.) (a) what is the probability that exactly two of the selected bulbs are rated 75-w

Answer 1

(a) what is the probability that exactly two of the selected bulbs are rated 75-w

Answer: We are given:

Six 40-w lightbulbs,

Four 60-w bulbs,

Three 75-w bulbs

Now the probability of exactly two 75-w bulbs is:

P( two 75-w bulbs) = $\frac{\binom{3}{2}\binom{10}{1}}{\binom{13}{3}}$

                              =$\frac{3 \times 10}{286}$

                              =$\frac{30}{286} =0.1049$

Therefore, the probability that exactly two of the selected bulbs are rated 75-w is 0.1049