A bottled water distributor wants to estimate the amount of water contained in 1​-gallon bottles purchased from a nationally known water bottling company. The water bottling​ company's specifications state that the standard deviation of the amount of water is equal to 0.02 gallons. A random sample of 50 bottles is​ selected, and the sample mean amount of water per 1​-gallon bottle is 0.985 gallons. Complete parts​ (a) through​ (d).

To compare the dry braking distances from 30 to 0 miles per hour for two makes of automobiles, a safety engineer conducts braking tests for 35 models of Make A and 35 models of Make B. The mean braking distance for Make A is 42 feet. Assume the population standard deviation is 4.7 feet. The mean braking distance for Make B is 45 feet. Assume the population standard deviation is 4.4 feet. At a = 0.10, can the engineer support the claim that the mean braking distances are different for the two makes of automobiles? Assume the samples are random and independent, and the populations are normally distributed. Complete parts (a) rari rz (b) Find the critical value(s) and identify the rejection region(s). The critical value(s) is/are (Round to three decimal places as needed. Use a comma to separate answers as needed.)

An energy company wants to choose between two regions in a state to install energy-producing wind turbines. A researcher claims that the wind speed in Region A is less than the wind speed in Region B. To test the regions, the average wind speed is calculated for 60 days in each region. The mean wind speed in Region A is 13.8 miles per hour. Assume the population standard deviation is 2.8 miles per hour. The mean wind speed in Region B is 15.1 miles per hour. Assume the population standard deviation is 3.1 miles per hour. At a = 0.05, can the company support the researcher's claim? Complete parts (a) through (d) below. C. The wind speed in Region A is not less than the wind speed in Region B. D. The wind speed in Region A is less than the wind speed in Region B. Let Region A be sample 1 and let Region B be sample 2. Identify Ho and Ha. Ho: H1 2 H2 Ha: 1 В. z C. z< - 1.645 (c) Find the standardized test statistic z. (Round to two decimal places as needed.)

Find the 95% confidence interval for the variance and standard deviation for the time it takes a state police inspector to check a truck for safety if a sample of 21 trucks has a standard deviation of 5.2 minutes. Assume the variable is normally distributed.