According to a report from Microsoft, 24% of PCs worldwide are not adequately protected by antivirus software.19 Suppose 200 PCs from around the world are selected at random.
a. Find the distribution of the sample proportion of PCs that are not adequately protected.
b. Find the probability that the sample proportion is less than 0.20.
c. Find the probability that the sample proportion is more than 0.29.
d. Find a value v such that the probability the sample proportion is less than v is 0.01.
Movie trailers are designed to attract large audiences. However, according to a recent survey, 32% of Americans believe movie trailers give away too many of a movie’s best scenes, that is, they reveal too much.20 Suppose 250 Americans are selected at random and asked if they believe movie trailers reveal too much.
a. Find the distribution of the sample proportion of Americans who believe movie trailers give away too much.
b. Find the probability that the sample proportion is more than 0.35.
c. Find the probability that the sample proportion is less than 0.25.
d. Find a symmetric interval about the mean (p 5 0.32) such that the probability that the sample proportion is in this interval is 0.90.