How large of a sample is required in order to be 90% sure that the sample proportion is off by no more than 2%?
Does a parent’s education level have anything to do with their involvement at their child’s school?
At the 0.01 level of significance, test the claim that educational attainment and volunteering at school are independent.
The president of a college wants to determine the mean number of units that college students take per semester. How large of a sample is required in order to be 99% sure that a sample mean will be off by no more than 1.25 units? An initial study suggested that the standard deviation is approximately 2.1 units.
Test the claim that the mean time required for high school students to run 1 mile is greater than 7 minutes at the 0.05 level of significance. Here are the results of a random sample of
25 students.
7.3 7.7 9.2 8.8 7.6 7.2 6.6 6.4 8.0
7.5 7.5 7.7 8.1 8.6 6.8 6.9 7.5
7.3 7.8 8.2 10.4 11.6 7.2 7.7 7.0
A sample of 200 smokers were asked at what age they started smoking. The meanage was 18.3 years. The population standard deviation is 4.35 years. Construct a 90% confidence interval for the mean age that all smokers begin smoking.
A random sample of 400 Spanish adults revealed that 143 were smokers. A random sampleof 300 American adults revealed that 70 were smokers. At the 0.05 level of significance, test the claim that the proportion of Spanish adults that smoke is greater than the proportion of American adults that smoke.
To test the claim that the mean blood glucose level of women is 100 mg/dL, a researcher takes a random sample of 135 women. They had a mean blood glucose level of 108.3 mg/dL.
(The population standard deviation is 3.4 mg/dL). Test the claim at the 0.05 level of significance.
A random sample of 50 bags of blue corn tortilla chips had a mean weight of 9.06 ounces, with a standard deviation of 0.05 ounces. A random sample of 50 jalapeno tortilla chips had a mean weight of 9.01 ounces, with a standard deviation of 0.03 ounces. At the 0.05 level of significance, test the claim that the mean fill of blue corn tortilla chip bags is the same as the mean fill of jalapeno tortilla chips.
A group of 9 concertgoers was selected at random. Before the concert they were given a hearing test, and then given another one after the concert. (The volume varied during the test, and the subject also had to state which ear the sound was in.) Here are the number of correctly identified sounds out of 10, both before and after the concert.
Person A B C D E F G H I
Before 9 10 9 8 8 9 9 9 8
After 8 8 9 6 6 7 10 8 5
At the 0.05 level of significance, test a person’s hearing is worse after being affected by the noise of a concert.
Construct a 90% confidence interval for the mean highway mileage for hybrid cars. A random sample of 8 hybrid cars had the following highway mileages in mpg.
36 41 37 45 50 40 32 39
Hole selections for professional golf courses are changed each day of a PGA tournament. Are any of the days set up to be more difficult or easier? Here are the scores of 7 golfers on the four days of a tournament.
Round 1 Round 2 Round 3 Round 4
63 65 68 65
66 67 68 67
66 67 70 67
70 65 66 69
67 68 69 67
68 67 70 67
68 67 67 70
At the 0.01 level of significance, test the claim that the mean scores produced by the four different rounds are equal.
In a survey of 500 women, 120 said that Valentine’s Day was their favorite occasion to receive flowers. Construct an 88% confidence interval for the proportion of all women who feel that Valentine’s Day is their favorite occasion to receive flowers
