21. Fifty rounds of a new type of ammunition were red from a test weapon, and the muzzle velocity of the projectile was measured. The sample had a mean muzzle velocity of 863 meters per second and a standard deviation of 2.7 meters per second. Construct and interpret a 99% confidence interval for the mean muzzle velocity. 22. in a February 2007 Harris Poll, 881 of 1,013 randomly selected adults said that they always wear seat belts. Construct and interpret a 98% confidence interval for the proportion of adults who always wear seat belts. Express the confidence interval in the form of [31 E. 23. A city cou ncilwoman selects a random sample of 12 streetlight service calls and obtains the following times to replacement (in days). Construct and interpret a 98% confidence interval for the mean amount of time for replacement of streetlights. 6.2 7.1 5.4 5.5 7.5 2.6 4.3 2.9 3.7 0.7 5.6 1.7 24. A simple random sample of size n = 320 adults was asked their favorite ice cream flavor. 0f the 320 individuals surveyed, 85 responded that they preferred mint chocolate chip. State [5. Construct and interpret a 95% confidence interval for the true percentage of all adults who prefer mint chocolate ice cream