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 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  = 0.01?
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 if $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 is Ocean City is greater than 24
years. She selects a sample of 26 guards 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 teacher claims that the boys in her classes are taller than the average 69 inches for boys in this age
group. The sample of 30 boys had an average height of 70.4 in. If the standard deviation for the height of
all boys in this age group is 2.75 inches, is there enough evidence to support the teacher’s claim at
  0.10 ?