# results from previous studies showed 79% of all high school seniors

1. Results from previous studies showed 79% of all high school seniors from a certain city plan to attend college after graduation. A random sample of 200 high school seniors from this city reveals that 162 plan to attend college. Does this indicate that the percentage has increased from that of previous studies? Test at the 5% level of significance.

State the null and alternative hypotheses.

A.H0: p ≤ .79, H1: p > .79

B.H0: p = .79, H1: p ≠ .79

C.H0: = .79, H1: > .79

D.H0: μ = .79, H1: μ > .79

2. A lab technician is tested for her consistency by taking multiple measurements of cholesterol levels from the same blood sample. The target accuracy is a variance in measurements of 1.2 or less. If the lab technician takes 16 measurements and the variance of the measurements in the sample is 2.2, does this provide enough evidence to reject the claim that the lab technician’s accuracy is within the target accuracy?

Compute the value of the appropriate test statistic.

A.Chi-sq = 27.50

B.z = 1.65

C.t = 27.50

D. = 30.58

3. A lab technician is tested for her consistency by taking multiple measurements of cholesterol levels from the same blood sample. The target accuracy is a variance in measurements of 1.2 or less. If the lab technician takes 16 measurements and the variance of the measurements in the sample is 2.2, does this provide enough evidence to reject the claim that the lab technician’s accuracy is within the target accuracy?

State the null and alternative hypotheses.

A.H0: σ2 ≠ 1.2, H1: σ2 = 1.2

B.H0: σ2 < 1.2, H1: σ2 ≠ 1.2

C.H0: σ2 ≤ 1.2, H1: σ2 > 1.2

D.H0: σ2 ≥ 1.2, H1: σ2 ≠ 1.2

4. Results from previous studies showed 79% of all high school seniors from a certain city plan to attend college after graduation. A random sample of 200 high school seniors from this city reveals that 162 plan to attend college. Does this indicate that the percentage has increased from that of previous studies? Test at the 5% level of significance.

What is the p-value associated with your test of hypothesis?

A.0.2437

B.0.6874

C.0.7563

D.0.4874

5.

The CEO of a software company is committed to expanding the proportion of highly qualified women in the organization’s staff of salespersons. He believes that the proportion of women in similar sales positions across the country is less than 45%. Hoping to find support for his belief, he directs you to test

H0: p ≥ .45 vs H1: p < .45.

In doing so, you collect a random sample of 50 salespersons employed by his company, which is thought to be representative of sales staffs of competing organizations in the industry. The collected random sample of size 50 showed that only 18 were women.

Compute the test value that you would use in conducting this test. Place your answer, rounded to 3 decimal places, in the blank. For example, -2.345 would be a legitimate entry.

5. The ABC battery company claims that their batteries last at least 100 hours, on average. Your experience with their batteries has been somewhat different, so you decide to conduct a test to see if the company’s claim is true. You believe that the mean life is actually less than the 100 hours the company claims. You decide to collect data on the average battery life (in hours) of a random sample of n = 20 batteries. Some of the information related to the hypothesis test is presented below.

Test of H0: >= 100 versus H1: < 100

Sample mean 98.5

Std error of mean 0.777

Assuming the life length of batteries is normally distributed, what is the p-value associated with this test? Place your answer, rounded to 3 decimal places in the blank. For example, 0.0234 would be a legitimate entry.

6. A medical doctor wishes to test the claim that the standard deviation of the systolic blood pressure of deep sea divers is less than 450. To do so, she selected a random sample of 20 divers and found s = 432.

Assuming that the systolic blood pressures of deep sea divers are normally distributed, if the doctor wanted to test her research hypothesis at the .01 level of significance, what is the critical value?

Place your answer, rounded to 3 decimal places, in the blank. For example, 4.567 would be a legitimate entry.

7. Suppose a firm that produces light bulbs wants to know whether it can say that its light bulbs typically last more than 1500 hours. Hoping to find support for their claim, the firm collects a random sample of n = 25 light bulbs and records the lifetime (in hours) of each bulb. The information related to the hypothesis test is presented below.

Test of H0: ≤ 1500 versus H1: > 1500

Sample mean 1509.5

Std error of mean 4.854

Assuming the life length of this type of lightbulb is normally distributed, if you wish to conduct this test using a .05 level of significance, what is the critical value that you should use? Place your answer, rounded to 3 decimal places in the blank. For example, 1.234 would be a legitimate entry.