An advertisement for ColdEx claims an 80 percent endoftreatm

An advertisement for Cold-Ex claims an 80 percent end-of-treatment clinical success rate for the treatment of flu. Twelve flu patients are given Cold-Ex and are later checked to see if the treatment was successful. Let\'s assume that the claim is correct.

1. Find the probability that exactly 8 have been cured.

2. Find the probability that at least 10 have been cured.

3. Find the probability that fewer than 5 have been cured.

4. Find the probability that between 6 and 9 (including 6 and 9) have been cured.

According to a recent study published in The Journal of Abnormal Psychology, 1 percent of seventh graders use marijuana weekly. Ten seventh graders are randomly selected across the country and are asked if they use marijuana weekly. Assuming that they are answering truthfully,

5. Find the probability that exactly 1 uses marijuana weekly.

6. Find the probability that fewer than four use marijuana weekly.

7. Find the probability that at least 5 use marijuana weekly.

A recent study found that of the patients receiving heart transplants after 1988, 83 percent were still alive. The files of six heart recipients are selected at random, and a follow-up study is made to see if each of the patients is alive.

8. Find the probability that exactly 4 are alive.

9. Find the probability that at least 5 are alive.

10. Find the probability that four or fewer are alive.

Solution