Answer:
0.7222 or 72.22%
Step-by-step explanation:
The probability that it takes at least two bulbs to pick a 75-W bulb is 100% minus the probability of getting a 75-W bulb with the first pick.
Since there are 5 75-W bulbs out of a total 18 bulbs, the probability is:
[tex]P(X\geq 2) = 1 - P(X=1)\\P(X\geq 2) = 1 -\frac{5}{18}\\ P(X\geq 2)=0.7222[/tex]
There is a 0.7222 or 72.22% probability that at least two bulbs must be selected to obtain one that is rated 75 W
