A tire company claims the lifetimes of its tires average 50,000 miles. The standard deviation of lifetimes is known to be 5000 miles. You sample 100 tires and will test the hypotheses that the mean tire lifetime is 50,000 miles against the alternative that it is less. Assume, in fact, that the true mean lifetime is 49,500. c) If the test is made at the 5% level, what is the power?

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.)

The average labor charge for automobile mechanics is OMR 69 per hour. The standard deviation is OMR 18. Find the minimum percentage of data values that will fall within the range of OMR 68 to OMR 80. Use Chebyshev's theorem. SHOW ALL THE WORKINGS, FORMULA etc.

You want to estimate the mean amount of time Internet users spend on Facebook each month. How many Internet users must be surveyed in order to be 90% confident that your sample mean is within 10 minutes of the population mean? Based on results from a prior survey, assume that the standard deviation of the population of monthly times spent on Facebook is 210 minutes.