Question

1. Which distribution is used to estimate a population mean?

1. The standard normal dist.(z)
2. None of these
3. The chi-square dist.
4. The t-dist

2. Which distribution is used to estimate a population proportion?

1. The t-dist
2. None of these
3. The chi-square dist
4. The standard normal (z) dist.

3. State the z critical value for a confidence level of 98%

1. 1.96
2. 2.576
3. 2.33
4. 1.645

4. In an effort to estimate the proportion of adults who smoke, a random sample of 125 adults contained 21 who smoke. Compute the Margin of Error if we use a confidence level of 99%

1. 8.1%
2. 8.9%
3. 9.1%
4. 8.6%

5. Find the t critical value for a sample of size 10 and confidence level 95%

1. 1.96%
2. 2.23%
3. 2.26%
4. 1.83%

6. In an effort to estimate the average(mean) age of automobiles currently in use, a random sample of 18 automobiles had a mean of 8 years and standard deviation 2.3 years. Compute the margin of error if we use a confidence level of 99%

1. 1.1 years
2. 1.3 years
3. 1.9 years
4. 1.6 years

7. Write the confidence interval estimate for a population proportion when the sample proportion(phat)= .31 and E=.05.

1. 26%<p<36%
2. 21%<p<41%
3. 29%<p<33%
4. 23%<p<39%

8. Write the confidence interval estimate for a population mean when the sample mean(x bar) is 169 pounds and the margin of error is 12 pounds.

1. 160 pounds<u<178 pounds
2. 156 pounds<u<180 pounds
3. 153 pounds<u<185 pounds
4. 165 pounds<u<173 pounds.

9. A random sample of 200 likely voters showed that 109 plan to vote for Ann. Write the 95% confidence interval estimate for the proportion of voters that will vote for ann.

1. 53%<p<57%
2. 51%<p<59%
3. 45%<p<65%
4. 48%<p<61%

10. A random sample of 16 fish showed a mean length of 23 inches and standard deviation 2.5 inches. Write the 95% confidence interval estimate for the mean length of fish of this type.

1. 22 inches<u<24 inches
2. 20 inches<u<26 inches
3. 19inches<u<27inches
4. 13inches<u<33 inches

Answer 1