An engineer has designed a valve that will regulate water pressure on an automobile engine. The valve was tested on 170 engines and the mean pressure was 4.2 lbs/square inch. Assume the standard deviation is known to be 0.6. If the valve was designed to produce a mean pressure of 4.1 lbs/square inch, is there sufficient evidence at the 0.1 level that the valve performs above the specifications? State the null and alternative hypotheses for the above scenario.

Do the mean weights of male college freshmen and male college seniors differ? There are arguments for and against this question. The mean weight, μx of college freshmen will be compared to the mean weight, My of college seniors. The true values of Mx and My are unknown. It is recognized that the true standard deviations are x = 13 for male college freshmen and dy = 24 for male college seniors. We take a random sample of m = 431 college freshmen and a random sample of n=289 college seniors. The mean weights were x = 178 for male college freshmen and y = 185 for male college seniors. Assuming independence between the samples and assuming the weights are normally distributed we would like to estimate My - My. a) What is the standard deviation of the distribution of x?[ b) What is the standard deviation of the distribution of x-y? c) Create a 95% confidence interval for Mx - Hy? d) What is the length of the confidence interval in part c) ? e) If we let n stay at 289 but vary m, what is the…

Biological oxygen demand (BOD) is a pollution index that is monitored in the treated effluent of paper mills. A certain paper mill has taken 31 samples over the past 3 months. The mean and standard deviation for the sample data are 3.42 and 0.728 ppm respectively. The mill would like to see if this sample indicates that the true average BOD in their treated effluent exceeds the targeted 3.00 ppm. Let ? = 0.05. A) The test statistic, (ttest), for this data set is: Note: Round your answer to the nearest hundredth.B) The p-value is: C) The statistical decision and corresponding English interpretation for this study are: Fail to reject Ha: conclude that the true BOD in treated effluent exceeds 3 ppmFail to reject Ho: we cannot conclude that the true BOD in treated effluent exceeds 3 ppm    Reject Ha: we cannot conclude that the true BOD in treated effluent exceeds 3 ppmReject Ho: conclude that the true BOD in treated effluent exceeds 3 ppm

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.

A population has parameters u = 189.5 and o = 61.9. You intend to draw a random sample of size n = 113. What is the mean of the distribution of sample means? What is the standard deviation of the distribution of sample means? (Report answer accurate to 2 decimal places.)

A population has parameters u = 239.9 and o = 18.4. You intend to draw a random sample of size n = 76. What is the mean of the distribution of sample means? What is the standard deviation of the distribution of sample means? (Report answer accurate to 2 decimal places.)

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?

A coin-operated drink machine was designed to discharge a mean of 7 fluid ounces of coffee per cup. In a test of the machine, the discharge amounts in 9 randomly chosen cups of coffee from the machine were recorded. The sample mean and sample standard deviation were 6.77 fluid ounces and 0.27 fluid ounces, respectively. If we assume that the discharge amounts are approximately normally distributed, is there enough evidence, to conclude that the population mean discharge, μ, differs from 7 fluid ounces? Use the 0.10 level of significance. Perform a two-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places. (If necessary, consult a list of formulas.) (a) State the null hypothesis Ho and the alternative hypothesis H₁. H₁ : μ = 7 H₁ μ‡7 (b) Determine the type of test statistic to use. Degrees of freedom: (c) Find the value of the test statistic. (Round to three or more decimal places.) t (d) Find the p-value. (Round to three or…