Sample surveys conducted in a large county in a cer-tain year and again 20 years later showed that originally the average height of 400 ten-year-old boys was 53.8inches with a standard deviation of 2.4 inches, whereas20 years later the average height of 500 ten-year-old boyswas 54.5 inches with a standard deviation of 2.5 inches.Use the four steps in the initial part of Section 1 andthe 0.05 level of significance to test the null hypothesisμ1 − μ2 = −0.5 against the alternative hypothesis μ1 −μ2 < −0.5.

A grocer finds that the cantaloupes in his store have weights with mean 0.7 kg and standard deviation 53 grams. If this is true, then 99.7% of cantaloupes will have weights between how many grams?

Suppose that the antenna lengths of woodlice are approximately normally distributed with a mean of 0.25 inches and a standard deviation of 0.05 inches. What proportion of woodlice have antenna lengths that are at least 0.18 inches? Round your answer to at least four decimal places.

Suppose that the heights of adult women in the United States are normally distributed with a mean of  64.5  inches and a standard deviation of  2.4  inches. Jennifer is taller than  80%  of the population of U.S. women. How tall (in inches) is Jennifer? Carry your intermediate computations to at least four decimal places. Round your answer to one decimal place. inches

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.)

Suppose an interval estimate for the population mean was 62.84 to 69.46. The population standard deviation was assumed to be 6.50, and a sample of 100 observations was used. The mean of the sample was:

Suppose that the antenna lengths of woodlice are approximately normally distributed with a mean of 0.22 inches and a standard deviation of 0.05 inches. What proportion of woodlice have antenna lengths that are at most 0.18 inches? Round your answer to at least four decimal places.

Consider the data from the Anthropology 105 class.  The mean for women is 64.33 in and the standard deviation is 2.64 in. The average height of men in the US is approximately 5ft 10in. What proportion of women represented here are shorter than the average man?

Solve step by step in digital format Suppose that the average income of the engineers hired at REDUNO presents an approximately normal behavior with a mean of $17,000 pesos and a standard deviation of $3,000 pesos. a) What percentage of the employees will have incomes greater than $20,000 pesos?b) In a random sample of 50 employees, about how many people can be expected to have incomes of less than $15,000 pesos?

The board of examiners that administers the real estate broker's examination in a certain state found that the mean score on the test was 494 and the standard deviation was 72. If the board wants to set the passing score so that only the best 10% of all applicants pass, what is the passing score? Assume that the scores are normally distributed. Round to the nearest whole number.