1. FInd a 90% confidence interval for the population variance if a sample of 12 had a variance of 360.
2. A car gets a mean of 18 mpg. Test to see if a cheaper gradde of gas makes any difference in the gas miles .01 level. A sample of 38 fillups with cheaper gas got a mean of 17.8 mpg and standard deviation of .6. State the hypothesis and identify the claim, find the critical value, compute test value, make decision and summarize.
3. AN emergency team responds to calls in a mean time of 8.4 minutes with a standard deviation of .7. If a sample of 18 calls with a new system generates a mean time of 7.8 minutes, test level .05 level. State the hypotheses, identify the claim, find the critical value, compute test value, make the decision, summarize the results.
4. A certain lottery claims that 10% of its tickets win prizes. sample of 50 tickets had 3 winners. At the .01 level, test the claim that the proportion is 10%. State the hypotheses, identify the claim, find the critical value, compute test value, make the decision, summarize the results.
5. Test at the .01 level the claim that the population variance is less than 158 if a sample of 10 had variance of 164. State the hypotheses, identify the claim, find the critical value, compute test value, make the decision, summarize the results.