Kevin has 11 CDs in his glove compartment. Six are rock and 5 are rap. He selects 3 cds at random.

What is the probability that he picks at least 2 rap cds?

Pr (two)=5/11 * 4/10 * 6/9

Pr (three ) =5/11 * 4/10 * 3/9

add those.

Not quite bobpursley.

There are 3 ways to pick 2 rap cds: (rap,rap,rock),(rap,rock,rap), and (rock,rap,rap). So,
Pr(two)=3*(5/11 * 4/10 * 6/9)
Pr(three) = same as before

add these.

14/33

To calculate the probability that Kevin picks at least 2 rap CDs, we need to consider two scenarios - when he picks exactly 2 rap CDs and when he picks all 3 rap CDs.

Scenario 1: Kevin picks 2 rap CDs:
There are 3 ways to pick 2 rap CDs - (rap, rap, rock), (rap, rock, rap), and (rock, rap, rap). The probability of each of these combinations occurring is:
Pr(two) = 3 * (5/11 * 4/10 * 6/9)

Scenario 2: Kevin picks all 3 rap CDs:
The probability of Kevin picking all 3 rap CDs is the same as before:
Pr(three) = 5/11 * 4/10 * 3/9

To calculate the probability that he picks at least 2 rap CDs, you need to add the probabilities of these two scenarios:
Pr(at least 2 rap) = Pr(two) + Pr(three)

To find the probability that Kevin picks at least 2 rap CDs out of the 3 CDs he selects, we need to calculate the probability of him picking exactly 2 rap CDs and exactly 3 rap CDs separately.

Let's first calculate the probability of him picking exactly 2 rap CDs. There are 3 ways this can happen: (rap, rap, rock), (rap, rock, rap), and (rock, rap, rap).

The probability of picking a rap CD on the first draw is 5/11 since there are 5 rap CDs out of 11 total CDs.

After picking a rap CD on the first draw, there are now 4 rap CDs left out of 10 total CDs, so the probability of picking another rap CD on the second draw is 4/10.

Finally, after picking two rap CDs, there are 6 rock CDs and 9 total CDs left, so the probability of picking a rock CD on the third draw is 6/9.

To find the probability of picking exactly 2 rap CDs, we multiply these probabilities together: 5/11 * 4/10 * 6/9.

Now let's calculate the probability of him picking exactly 3 rap CDs. The probability of picking a rap CD on the third draw, after picking two rap CDs previously, is the same as before: 5/11 * 4/10 * 3/9.

To find the overall probability of picking at least 2 rap CDs, we need to add together the probabilities of picking exactly 2 rap CDs and exactly 3 rap CDs:

Pr(at least 2 rap CDs) = 3 * (5/11 * 4/10 * 6/9) + (5/11 * 4/10 * 3/9)

So, the probability that Kevin picks at least 2 rap CDs is obtained by adding these two probabilities.