AP Stats
HW 5 - Hypothesis Tests for Means
Name_______________________________________
1. A machine is designed to fill jars with 16 ounces of coffee. A consumer suspects that the machine is not
filling the jars completely. They sampled 12 jars shown below. Is there enough evidence to support the
consumer’s claim at   0.10 ?
15
15.4
16.2
16.1
15.8
16.2
15.7
15.6
16
16.3
15.3
15.9
2. A researcher reports that the average salary of assistant professors is more than $42,000. A sample of 32
assistant professors has a mean salary of $43,260. At   0.05 , test the claim that assistant
professors earn more than $42,000 a year. The standard deviation is known to be $5,230.
3. The Medical Rehabilitation Foundation reports that the average cost of rehabilitation for stroke victims is
$24,672. To see if the average cost of rehabilitation is different at a large hospital, a researcher selected
a random sample of 25 stroke victims and found that the average cost of their rehabilitation is $25,266
with a standard deviation of $3,251. At   0.01 can it be concluded that the average cost at a large
hospital is different?
4. A researcher wishes to test the claim that the average age of lifeguards in Ocean City is greater than 24
years. She selects a sample of 26 lifeguards and finds the mean of the sample to be 24.7, with a standard
deviation of 2 years. Is there evidence to support the claim at   0.05 ?
5. The proportion of college students who gain weight their first year is at least 65%. To test this,
researchers sampled 200 students and found 120 had gained weight their first year. Use a 5% significance
level.
6. A physician claims that jogger’s maximal volume oxygen uptake is greater than the average of all adults. A
sample of 15 joggers has a mean of 43.6 ml per kg and a standard deviation of 6 ml/kg. If the average of all
adults is 36.7 ml/kg, is there enough evidence to support the physician’s claim at   0.10 ?