1. A laptop battery manufacturer claims that the mean life of its new battery is at least 9.75 hours. Thirty-two of the new batteries are randomly sampled; here are the data in hours:

7.91, 9.43, 10.39, 9.77, 8.61, 9.64, 9.04, 7.97, 9.77, 11.05, 9.25, 9.21, 9.44, 10.13,

10.96, 11.87, 7.08, 9.93, 11.25, 8.18, 11.22, 10.00, 9.55, 9.91, 8.81, 9.22, 10.22,

9.37, 9.47, 9.95, 8.96, 8.40

Assume the data are normally distributed. What is the p-value in a test of the claim? Round your answer to four decimal places.

2. A researcher studies the relationship between the presence/absence of plant species based on a quantitative measurement of habitat quality. Below is the output using habitat quality to predict the probability of the plant species being present:

	Estimate	SE	z	Pr(>|z|)
(Intercept)	-9.37	2.15	-3.85	0.0252
habitat quality	0.41	0.09	4.41	0.0092

What is the predicted probability of the plant species being present when habitat quality = 19.2? Round your answer to four decimal places.

3. A claim is made that among U.S. households, 24% use an accountant to prepare their taxes, 20% do their own taxes by hand, 35% use computer software, 6% have a friend or family do their taxes, and 15% use a tax preparation service.

To test the claim, 300 U.S. households are randomly sampled to determine how each prepares their taxes. Below are the data from the random sample:

Method of preparing taxes	Number of U.S. households
Accountant	61
By hand	42
Computer software	112
Friend/family	29
Tax preparation service	56

The value of the test statistic in a test of the claim is

this answer to three decimal places.

. Round

The degrees of freedom in a test of the claim is

.