Reject Ho

Do not reject Ho

7. The following information is obtained from two independent samples selected from two normally distributed populations.

n1 = 18 x1 = 7.82 σ1 = 2.35

n2 =15 x2 =5.99 σ2 =3.17

A. What is the point estimate of μ1 − μ2? Round to two decimal places.

B. Find the margin of error for this estimate. Construct a 99% confidence interval for μ1 − μ2.

Round to two decimal places.

**) **8. The following information is obtained from two independent samples selected from two populations.

n1 =650 x1 =1.05 σ1 =5.22

n2 =675 x2 =1.54 σ2 =6.80

Test at a 5% significance level if μ1 is less than μ2.

a). Identify the appropriate distribution to use.

- t distribution
- normal distribution

b.) What is the conclusion about the testing the null hypothesis?

- Reject Ho
- Do not reject Ho

9. Using data from the U.S. Census Bureau and other sources, www.nerdwallet.com estimated that considering only the households with credit card debts, the average credit card debt for U.S. house- holds was $15,523 in 2014 and $15,242 in 2013. Suppose that these estimates were based on random samples of 600 households with credit card debts in 2014 and 700 households with credit card debts in 2013. Suppose that the sample standard deviations for these two samples were $3870 and $3764, respectively. Assume that the standard deviations for the two populations are unknown but equal.

a) Let μ1 and μ2 be the average credit card debts for all such households for the years 2014 and 2013, respectively. What is the point estimate of μ1 − μ2? Round to two decimal places.

b)Construct a 98% confidence interval for μ1 − μ2. Round to two decimal places. Do not include the dollar sign.

- What is the lower bound? Round to two decimal places.

2. What is the upper bound? Round to two decimal places.