MATH 534 Week 4 Addendum; Homework-Quiz Review Problems and Notes

1. Question: A consumer protection agency wants to study gas prices at gas stations in the state. It takes a sample of 50 gas stations. The sample mean is $2.35 with a standard deviation of $0.12. Construct a 99% confidence interval to estimate the population mean. 2. Question: A consumer protection agency wants to study gas prices at gas stations in the state. It takes a sample of 50 gas stations. The sample mean is $2.35. The population standard deviation is known to be $0.10. Construct a 99% confidence interval to estimate the population mean. 3. Question: A consumer protection agency wants to study gas prices at gas stations in the state. It takes a sample of 50 gas stations. The sample mean is $2.35 with a standard deviation of $0.12. What is the point estimate of the population mean of the gas prices? 4. Question: We take a sample of 36 students and find that 12 of them are from New Jersey. The point estimate of the population proportion of the students that are from New Jersey is. 5. Question: We take a sample of 200 cars. 35% of them are white. The 90% confidence interval to estimate the population proportion is. 6. Question: We want create a 99% confidence interval to estimate the population mean of the number of heartbeats per minute for adults. We want the estimate to be within 3 beats of the actual population mean. The population variance is estimated to be around 24. The necessary sample size should be at least. 7. Question: We want create a 99% confidence interval to estimate the population mean of the number of heartbeats per minute for adults. We want the estimate to be within 3 beats of the actual population mean. The lowest number of heartbeats per minute that we have seen is 50 and highest in 80. The necessary sample size should be at least. 8. Question: We want to create a 90% confidence interval to estimate the proportion of voters who support Superman for president. In the past, about 43% of the people have said they would vote for him. We are willing to be off by 7% (i.e. .07). The sample size should be at least. 9. Question: We want to create a 90% confidence interval to estimate the proportion of voters who support Superman for president. We don’t have any previous knowledge of the proportion who support Superman. We are willing to be off by 7% (i.e. .07). The sample size should be at least. 10. Question: The z value associated with a two-sided 80% confidence interval is. 11. Question: The table t value associated with the upper 7% of the t distribution and 23 degrees of freedom is _______________.