A software company is trying to decide whether to produce an upgrade of one of its programs. Customers would have to pay $100 for the upgrade. For the upgrade to be profitable, the company has to sell it to more than 20% of their customers. You contact a random sample of 60 customers and find that 16 would be willing to pay$100 for the upgrade. Do the sample data give convincing evidence at the $\alpha=0.05$ significance level that more than 20% of the company's customers are willing to purchase the upgrade?

Write a short paragraph about a sports experience you have had. Try to include a direct object in every sentence. Then, underline each direct object.

What is the sticker price? Sports car. Base price is $17,495. Options: Anti-lock brakes for$500. Automatic transmission for $995. Destination charge is$400.

Peter is a star runner on the track team. In the league championship meet, Peter records a time that would fall at the 80th percentile of all his race times that season. But his performance places him at the 50th percentile in the league championship meet. Explain how this is possible. (Remember that lower times are better in this case!)

Given a binomial experiment with probability of success on a single trial p=0.30, find the probability that the first success occurs on trial number n=2.

In this problem, you are asked to solve part of the Focus Problem at the beginning of this chapter. In his book Chances: Risk and Odds in Everyday Life, James Burke says that there is a 72% chance a polygraph test (lie detector test) will catch a person who is, in fact, lying. Furthermore, there is approximately a 7% chance that the polygraph will falsely accuse someone of lying. Suppose a person answers 10% of a long battery of questions with lies. What percentage of the answers will the polygraph correctly indicate are lies?

(a) What are the hypotheses in a chi-square test for independence? (b) Why do we call it a test of frequencies? (c) What distribution is used in this test? (d) How do we calculate the degrees of freedom for an $r \times c$ contingency table?

Calculate the test statistic, and determine whether there is enough evidence to reject the null hypothesis. Then make a statement regarding the original claim. A teacher claims that the average cost of a certain brand of graphing calculator is at least $90. A random sample of 40 stores shows that the mean cost is$89.25 with a standard deviation of $4.95. Is there enough evidence to reject the teacher's claim at$\alpha=0.05 ?$ Explain.

A drug company has developed a new vaccine for preventing the flu. The company claims that fewer than 5% of adults who use its vaccine will get the flu. To test the claim, researchers give the vaccine to a random sample of 1000 adults. Of these, 43 get the flu. Do these data provide convincing evidence to support the company's claim?

Check that the conditions for carrying out a one-sample z test for the population proportion p are met. A recent report claimed that 13% of students typically walk to school. DeAnna thinks that the proportion is higher than 0.13 at her large elementary school, so she surveys a random sample of 100 students to find out.

A college president says, "More than two-thirds of the alumni believe I should fire Coach Harbaugh." The president's statement is based on 200 emails he has received from alumni in the past three months. The college's athletic director wants to perform a test of $H_0$: p=2/3 versus $H_a$: p>2/3, where p= the proportion of all the college's alumni who favor firing the coach. Check if the conditions for performing the significance test are met.

A penny and a nickel are tossed. The penny has probability 0.4 of coming up heads, and the nickel has probability 0.6 of coming up heads. Let X = 1 if the penny comes up heads, and let X = 0 if the penny comes up tails. Let Y = 1 if the nickel comes up heads, and let Y = 0 if the nickel comes up tails. a. Find the probability mass function of X. b. Find the probability mass function of Y. c. Is it reasonable to assume that X and Y are independent? Why? d. Find the joint probability mass function of X and Y.

Name the organs that help rid the body of waste. What type of waste does each organ remove?

Which of the following terms refers to an increase in cell size? a. Hyperplasia b. Hypertrophy c. Anaplasia d. Atrophy