Chapter 5: Q 9. (page 294)
Due to a hit, A very good professional baseball player gets a hit about of the time over an entire season. After the player failed to hit safely in six straight at-bats, a TV commentator said, “He is due for a hit by the law of averages.” Is that right? Why?
It was not right.
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Fill ’er up Refer to Exercise 83. Given that the customer paid with a credit card, find the probability that she bought premium gas.
Fill ’err up! In a recent month, of automobile drivers filled their vehicles with regular gasoline, purchased midgrade gas, and bought premium gas. Of those who bought regular gas, paid with a credit card; of customers who bought midgrade and premium gas, and , respectively, paid with a credit card. Suppose we select a customer at random.
Draw a tree diagram to represent this situation. What’s the probability that the customer paid with a credit card? Use the four-step process to guide your work.
Free downloads? Illegal music downloading has become a big problem: of Internet users download music files, and of downloaders say they
don’t care if the music is copyrighted.15 What percent of Internet users download music and don’t care if it’s copyrighted? Write the information given in terms of probabilities, and use the general multiplication rule.
Recycling Do most teens recycle? To find out, an AP Statistics class asked an SRS of 100 students at their school whether they regularly recycle. How many students in the sample would need to say “Yes” to provide convincing evidence that more than half of the students at the school recycle? The Fathom dot plot below shows the results of taking 200 SRSs of 100 students from a population in which the true proportion who recycle is 0.50.
(a) Suppose 55 students in the class’s sample say “Yes.” Explain why this result does not give convincing evidence that more than half of the school’s students recycle.
(b) Suppose 63 students in the class’s sample say “Yes.” Explain why this result gives strong evidence that a majority of the school’s students recycle.
Construct a tree diagram to represent this situation.
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