The piston diameter of a certain hand pump is 0.6 inch. The manager determines that the diameters are normally​ distributed, with a mean of 0.6 inch and a standard deviation of 0.005 inch. After recalibrating the production​ machine, the manager randomly selects 21 pistons and determines that the standard deviation is 0.0044 inch. Is there significant evidence for the manager to conclude that the standard deviation has decreased at the α=0.05 level of​ significance?

An engineer working for a tire manufacturer investigates the average life of a new material to be used in the manufacturing process. For this purpose, he builds a sample of 13 tires and tests them in a laboratory until the end of their useful life is reached. The data obtained from the sample are as follows: average of 60897.9 km and standard deviation of 2734.8 km. The engineer would like to demonstrate that the average service life of the tire with the new material exceeds 60,000 km. a) State the null and alternative hypothesis to be stated in this experiment. Test the stated hypotheses using an α = 0.05 What conclusions are reached? b) Find a 95% confidence interval for the average tire life with the new material. Interpret your answer.   (RESPOND MANUALLY) (RESPOND MANUALLY)

A light bulb manufacturer guarantees that the mean life of a certain type of light bulb is at least 754 hours. A random sample of 30 light bulbs has a mean life of 732 hours. Assume the population is normally distributed and the population standard deviation is 62 hours. At a = 0.05, do you have enough evidence to reject the manufacturer's claim? Complete parts (a) through (e). Zo = - 1.65 (Use a comma to separate answers as needed. Round to two decimal places as needed.) Identify the rejection region(s). Choose the correct answer below. O A. B. O C. Fail to reject H- Fail to reject Ho Fail to reject Ho- Reject Ho Reject Ho Reject Ho Reject H,- -4

Suppose babies born after a gestation period of 32 to 35 weeks have a mean weight of 2600 grams and a standard deviation of 600 grams while babies born after a gestation period of 40 weeks have a mean weight of 2900 grams and a standard deviation of 440 grams. If a 35-week gestation period baby weighs 2775 grams and a 40-week gestation period baby weighs 3075 grams, find the corresponding z-scores. Which baby weighs more relative to the gestation period? Find the corresponding z-scores. Which baby weighs relatively more? Select the correct choice below and fill in the answer boxes to complete your choice. (Round to two decimal places as needed.) A. The baby born in week 40 weighs relatively more since its z-score, is smaller than the z-score of for the baby born in week 35. B. The baby born in week 40 weighs relatively more since its z-score, is larger than the z-score of for the baby born in week 35. O C. The baby born in week 35 weighs relatively more since its z-score, is larger…

The blood platelet counts of a group of women have a​ bell-shaped distribution with a mean of 264.8264.8 and a standard deviation of 60.960.9. ​(All units are 1000 ​cells/muμ​L.) Using the empirical​ rule, find each approximate percentage below. a. What is the approximate percentage of women with platelet counts within 11 standard deviationdeviation of the​ mean, or between 203.9203.9 and 325.7325.7​? b. What is the approximate percentage of women with platelet counts between 82.182.1 and 447.5447.5​?

In a certain country the heights of adult men are normally distributed with a mean of 69.7 inches and a standard deviation of 2.5 inches. The country's military requires that men have heights between 65 inches and 76 inches. Determine what percentage of this country's men are eligible for the military based on height. The percentage of men that are eligible for the military based on height is (Round to two decimal places as needed.) %. (1) U +

An obstetrician read that a newborn baby loses on average 7 ounces in the first two days of his or her life. He feels that in the hospital where he works, the average weight loss of a newborn baby is less than 7 ounces. A random sample of 30 newborn babies has a mean weight loss of 6.4 ounces. The population standard deviation is 1.6 ounces. Is there enough evidence at =α0.01 to support his claim? Assume that the variable is normally distributed. Use the critical value method with tables. hello the question askas to find the critical value compute the test value and select the hypothesis

A company that makes cola drinks states that the mean caffeine content per 12-ounce bottle of cola 40 milligrams. You want to test this claim. During your tests, you find that a random sample of thirty 12-ounce bottles of cola has a mean caffeine content of 39.2 milligrams. Assume the population is normally distributed with a standard deviation of 7.5 milligrams. At α=0.01, can you reject the company’s claim?