Name: ______________________________________ Date: ______________________________ Period: ______
AP Statistics
3rd Quarter Exam Practice #3
1. List the conditions, test statistic equation, confidence interval formula, and calculator function used for each below:
Conditions
Test Statistic
Confidence Interval
Two Means:
Independent
Two Means:
Matched Pair
Two Proportions:
[SKIP – This is for Chapter 25, which is not on the Quarter Exam]
Calculator
2. Scientists have linked a catastrophic decline in the number of frogs inhabiting the world to increased ultraviolet
radiation from a depleting ozone. Researchers at Oregon State University compared the hatching rates of two
groups of Pacific Tree frog eggs. One group of eggs was shielded with ultraviolet-blocking-sunshades, while the
second group was not. Test the claim that the proportion of eggs that hatch from the sun-shaded group is less than
the proportion of eggs hatched from the non-shaded group at the 0.01 level of significance.
Sun-shaded
number
hatched
total
number
Non-shaded
24
36
60
60
Create a 95% confidence interval of the difference of proportions between sun-shaded and non-shaded.
3. Nielsen Median Research reported that adult women watch TV an average of 5 hr and 1 min per day, compared to
an average of 4 hr and 17 min for adult men. Assume that those results are found from a sample of 100 men and
100 women and that the two groups have the same standard deviation of 57 min. Test the claim that women watch
more TV than men.
Use α =0.01
4. Baby walkers are seats hanging from frames that allow babies to sit upright with their legs dangling while their feet
touch the floor. Because most walkers have tray tables in front that block babies’ views of their feet, child
psychologists have begun to question whether walks affect infants’ cognitive development. Mental skill scores
averaged 113 for the 41 babies who used walkers with a standard deviation of 12 and 123 for 41 babies who did not
use walkers with a standard deviation of 15. Test the claim that the mean mental skill score of babies who use baby
walkers is less than the mental skill scores of babies who do not use walkers at the 0.01 level of significance.
Create a 90% confidence interval of the difference mental skill scores of using a walker and not using a walker.
5. The Minton Motor Products Company produced a new type of spark plug and mails advertisements that the spark
plug improves fuel consumption. The U.S postal Service charges the company with mail fraud on the basis that
these new plugs are no better than the current spark plugs on the marker. Sample data are collected by testing the
new plugs and ordinary plugs in a random sample of cars. The results are given below as distances in miles that cars
travel on 1 gallon of gas. At the 0.05 level of significance, test Minton’s claim that the new plugs improve the mean
miles per gallon.
car
Minton
Ordinary
1
2
3
4
5
6
7
8
9
18.2 23.4 19.7 14.7 28.7 23.4
19 21.2 18.2
16.1 21.3 19.2 14.8 29.3 20.2 18.6 19.7 16.4
[SKIP – This is from Chapter 25, which is not on the Quarter Exam]
6. In order to increase egg production, a farmer decides to increase the amount of time the lights in the hen house
were on. Ten hens were selected, and the number of eggs each produced was recorded. After one week of
lengthened light time, the same hens were monitored again. The data are given in the table below. At a 5% level of
significance, test the farmer’s hypothesis that the increased light time would increase egg production.
Hen
Before
After
1
4
6
2
3
5
3
8
9
4
7
7
5
6
4
6
4
5
[SKIP – This is from Chapter 25, which is not on the Quarter Exam]
Construct a 99% confidence interval for the difference of means.
[SKIP – This is from Chapter 25, which is not on the Quarter Exam]
7
9
10
8
7
6
9
6
9
10
5
6
7. When games were sampled from a season, it was found that the home team won 127 of 198 professional basketball
games and the home team won 57 of 99 professional football games. Test the claim that the rate of home wins for
basketball and football games is the same.
Construct a 90% confidence interval for the difference between the proportions of home wins.