1. Worksheet for Hypothesis Tests for Means
Section 10-4

2. 1. A machine is designed to fill jars with 16 ounces of coffee
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
15.7
15.6 16
16.3
15.3
15.9

3. µ = Means amount of ounces of coffee in a jar.
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 α = 0.10?
µ = Means amount of ounces of coffee in a jar.
Assumptions:
SRS
Approx. Normal (Pop)
Independent: 10(12)=120
Use a T-Test since σ is unknown and n<30. df=11
Reject the Ho since P-value (0.0505)<α (0.10).
There is sufficient evidence to support the claim that the mean number of ounces of coffee is less than 16 ounces.

4. 2. A researcher reports that the average salary of assistant professors is more than $42,000. A sample of 30 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 $5,230.

5. µ = Mean salary of assistant professors
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 α = 0.05, test the claim that assistant professors earn more than $42,000 a year. The standard deviation is $5,230. .
µ = Mean salary of assistant professors
Assumptions:
SRS
Approx. Normal since n>30
Independent: 10(32)=320
Use a Z-Test since σ is known
Fail toReject the Ho since P-value (0.087)>α (0.05).
There is insufficient evidence to support the claim that the mean salary of assistant professors is more than $42000.

6. 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 35 stroke victims and found that the average cost of their rehabilitation if $25,266. The st. dev. Is $3,251. At = 0.01, can it be concluded that the average cost at a large hospital is different?

7. 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. The st. dev. Is $3,251. At α = 0.01
µ = average cost of rehabilitation for stroke victims
Assumptions:
SRS
Approx. Normal (Pop)
Independent: 10(25)=250
use T-test since σ is unknown & n< 30. df=24
Fail to Reject the Ho since P-value (0.37)>α (0.01).
There is insufficient evidence to support the claim that the mean cost of rehabilitation for stroke victims is different from $24,672.

8. 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 36 guards and finds the mean of the sample to be 24.7, with a st. dev. Of 2 years. Is there evidence to support the claim at = 0.05?

9. 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 st. dev. Of 2 years. Is there evidence to support the claim at α = 0.05?
µ = Mean age of lifeguards in Ocean City.
Assumptions:
SRS
Approx. Normal (pop)
Independent: 10(26)=260
Use a t dist. Since σ is unknown & n<30. df=25
Reject the Ho since P-value (0.044)<α (0.05).
There is sufficient evidence to support the claim that the mean age of lifeguards is more than 24 years old.

10. 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 130 had gained weight their first year. Use a 5% significance level.

11. 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.
p = Pop. Prop. of college students who gain weight their first year.
Assumptions:
SRS
Approx. Normal
Independent 10(200)=2000
Use a Z-Test for Prop.
Fail to Reject the Ho since P-value (0069)>α (0.05).
There is insufficient evidence to support the claim that the proportion of college students who gain weight their first year is less than 65%.

12. 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 = 0.01?

13. 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 = 0.01?
µ = Mean volume of oxygen uptake for joggers
Assumptions:
SRS
Approx. Normal (Pop)
Independent: 10(15)=150
use t-test since σ is unknown & n<30.
Df=14
Reject the Ho since P-value (0)<α (0.01).
There is sufficient evidence to support the claim that the mean volume of oxygen uptake for joggers is greater than 36.7m.per kg.