Dullco Manufacturing claims that its alkaline batteries last at least 40 hours on average in a certain type of portable CD player. But tests on a random sample of 18 batteries from a day’s large production run showed a mean battery life of 37.8 hours with a standard deviation of 5.4 hours. To test DullCo’s hypothesis, the p-value is   Multiple Choice   slightly less than .05.   slightly greater than .05.   uncertain without knowing α.   exactly equal to .05.

The yield per tract in a certain region of farmland is known to have a populationstandard deviation of 13 bushels. Using the old seed variety, the population mean yield μwas 39 bushels. A farmer tests a new seed variety on a random sample of 36 tracts, andfinds a sample mean yield of 45.2 bushels. Is the population mean yield using the newseed variety different from 39? Use α= 0.10.a. State the null hypothesis . __________________State the alternative hypothesis.____________________b. Find the test statistic. _____ c. Find the P-value for the test. _____________

A random sample of 90 eighth grade students' scores on a national mathematics assessment test has a mean score of 288. This test result prompts a state school administrator to declare that the mean score for the state's eighth graders on this exam is more than 280. Assume that the population standard deviation is 36. At α = 0.08, is there enough evidence to support the administrator's claim? Complete parts (a) through (e). (a) Write the claim mathematically and identify Ho and H₂. Choose the correct answer below. A. Ho: μ = 280 (claim) Ha:μ>280 Ho:μ≤280 Ha: μ> 280 (claim) B. Ho: μ = 280 P-value = (b) Find the standardized test statistic z. z = 2.11 (Round to two decimal places as needed.) (c) Find the P-value. E. Ho: μ≤280 (claim) Ha:μ>280 Ha: μ> 280 (claim) (Round to three decimal places as needed.) C. Ho: μ ≥280 (claim) Ha:μ< 280 F. Ho: μ< 280 H₂:μ ≥280 (claim)

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 43 feet. Assume the population standard deviation is 4.6 feet. The mean braking distance for Make B is 46 feet. Assume the population standard deviation is 4.5 feet. At α=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.   The critical​ value(s) is/are   Find the standardized test statistic z for μ1−μ2.