# 1. (Chapter 7: Estimating a Population Proportion) a Poll Sample of 500 People Was Conducted

1. *(Chapter 7: Estimating a Population Proportion) **A poll sample of 500 people was conducted if they support new initiative. **200 people said yes. Find the margin of error E and confidence interval for population proportion Apply Confidence Level CL=0.90 (90%).**You can find critical value za/2, required for calculation, in small table given in our **textbook on page 329 Edition 12 or page 332 in Edition 11.*

2. *(Chapter 7: Estimating a Population Mean).**Sample of 100 measurements were taken to analyze concentration of impurities in a product. Calculated sample mean was 65ppm (parts per million). Assuming that population standard deviation is 20 ppm, estimate margin of error and confidence interval for population mean with confidence level 95%. Round the answer up to the whole numbers.*

3. *(Chapter 7) Find the critical value ta/2 for estimate procedure when population standard deviation is not known. Sample size is n=24, Confidence Level 98%.**Tip: Use column with Area in Two Tails in t-Distribution table.*

4. *(Chapter 7) Sample of 30 people randomly asked in casino shows that average lost per person is $160 with a sample standard deviation s = $40. Based on this data create a 95% confidence interval for population mean. This is the case where population standard deviation is not known and you have to use Appendix table A-3 for t-value.**Round the answer up to the whole numbers.*

5. *(Chapter 8) Use Appendix Table A-2 to find the critical z value for right-tail test with significance level α = 0.10.*

6. *(Chapter 8) Show on the z number line critical/rejection region for the Two-Tailed Hypothesis testing with significance level α = 0.08 (use highlight or shading like in Conference for week 6).*

7.* (Chapter 8) Use Appendix Table A-2 to find p-value for a left-tail test *

with test statistics z = - 1.24.

8. *Chapter 8: The P-value of a hypothesis test is 0.0345. **Which of the following claims is correct?*

*A) Reject Ho at the 0.05 significance level but not the 0.01 significance level.*

*B) Reject Ho at the 0.01 significance level but not the 0.05 significance level.*

*C) Reject Ho at both the 0.01 significance level and the 0.05 significance level.*

*D) Do not reject Ho at significance level 0.01and do not reject Ho at the 0.05 significance level.**Chapter 8: Testing Claim about a Proportion.*

*For questions 9, 10, 11 use following data:*

*Evaluate the claim that percent of small businesses closed this year (population proportion) is greater than 26%. Sample of 500 small businesses were taken all over the country and 145 of them were closed this year. *

H0 – population proportion p = 0.26*H1 – population proportion p > 0.26*

9.*Calculate z-value for test statistics*

10. Use Table A-2 to find p-value.

11.*At significance level 0.05 reject or do not reject H0. Explain your decision. **Chapter 8: Testing Claim for Population Mean, population standard deviation is known*

For questions 12, 13 use following data

Consider the hypothesis test with

Null Hypothesis Ho: μ = 500

Alternative Hypothesis H1: μ≠500 (this is two-tailed test)

In a random sample of 81 subjects, the sample mean found to be x=492.

Population standard deviation is σ=36.

12.Calculate test statistics and find P-value for this test (use Appendix table A-2).

13.With significance level α = 0.02 (remember, this is two-tailed test) make the decision:

accept or reject Ho. Explain your decision

Chapter 8: Testing Hypothesis for Population Mean, population standard deviation not known.

Instead, sample standard deviation is given.

For questions 14 use the following data.

With sample size n=36, sample mean 710 and sample standard deviation s = 30

Null Hypothesis Ho: μ = 700

Alternative Hypothesis H1: μ 700 (this is right-tailed test)

Significance level α = 0.05

14. Calculate t-value for the test statistics.

In Table A-3 for t-distribution find critical value. Use column with Area in One Tail 0.05.

Identify rejection region as area to the right of critical value from Table A-3.

Is value of test statistics falls in the rejection region?

Will you reject or do not reject the Null Hypothesis?