Of 139 adults selected randomly from one town, 30 of them smoke. Construct a 99% confidence interval for the true percentage of all adults in the town who smoke.
A sample of 10 body temperatures has a mean of 98.2 degrees F and a sample standard deviation of .62 degrees F.
a) Construct a 95% confidence interval of the mean body temperature for the entire population
b) Construct a 95% confidence interval for the variance and standard deviation of the entire population.
39 packages are randomly selected from packages received by a parcel service. The sample mean weight is 15.3 pounds. From previous samples we know the population standard deviation 1.9 pounds. Construct at 95% confidence interval for the true mean weight of all packages received by the parcel service.
President Biden- is proposing health care reform and wants to know how many people he needs to survey in Massachusetts to see if they favor his reform package and what % age.
a) If no previous survey is available, how many people do his pollsters need to interview?
b) If a prelim study found 98% of Mass residents favor his plan, with a margin of error set 2%, how many people does he needs to survey?
Nielsen Media Research wants to estimate the mean amount of time (in minutes) that full-time college students spend watching television each week day. Find the sample size necessary to estimate the mean with a 15-minute margin of error. Assume a 90% confidence interval is desired. Also assume that a pilot study showed that the standard deviation is estimated to be 112.2 minutes.