A box contains seven 40-W bulbs, six 60-W bulbs, and eight 75-W bulbs. If bulbs are selected one by one in random order, what is the probability that at least two bulbs must be selected to obtain one that is rated 75 W? (Round your answer to three decimal places.)

And if we replace we got:

Step-by-step explanation:

Previous concepts

The geometric distribution represents "the number of failures before you get a success in a series of Bernoulli trials. This discrete probability distribution is represented by the probability density function:"

Let X the random variable that measures the number os trials until the first success, we know that X follows this distribution:

Solution to the problem

For this case the totla number of bulbas are: 7+6+8= 21

For this case we have eight 75W

And we can find the probability of success on this case like this:

And let X the random variable that represent the number of 75-W bulbs, then we have that

And we want to find this probability:

We can use the complement rule and we have:

And if we replace we got:

8

step-by-step explanation:

just put √(2) * √(32) into a calculator. that will make the answer be 8.

so what is the problem what are they asking you to solve

step-by-step explanation:

so what is the problem what are they asking you to solve