High-power experimental engines are being developed by the Stevens Motor Company for use in its new sports coupe. The engineers have calculated the maximum horsepower for the engine to be 800 HP. Twenty five engines are randomly selected for horsepower testing. The sample has an average maximum HP of 870 with a standard deviation of 80 HP. Assume the population is normally distributed. Step 1 of 2: Calculate a confidence interval for the average maximum HP for the experimental engine. Use a significance level of a = 0.01. Round your answers to two decimal places.

The quality control manager of a car antifreeze manufacturer wants to find the fluctuations in the amount of antifreeze solution that a container can hold.  She selects a sample of 18 such container and arrives at an average of 3787 lb., and a s.  d. of 55.4 lb.   Using this sample data construct a 95% confidence interval for the standard deviation of the car antifreeze.

Using traditional methods it takes 8.2 hours to receive a basic flying license. A new license training method using Computer Aided Instruction (CAI) has been proposed. A researcher used the technique on 26 students and observed that they had a mean of 8.0 hours with a variance of 2.89. Is there evidence at the 0.1 level that the technique reduces the training time? Assume the population distribution is approximately normal. Step 5 of 5: Make the decision to reject or fail to reject the null hypothesis.

Assume that a simple random sample has been selected from a normally distributed population.  State the final conclusion.Test the claim that the mean lifetime of car engines of a particular type is greater than 220,000 miles. Sample data are summarized as n = 23,  and s = 11,500 miles. Use a significance level of α = 0.01.H0: μ = 220,000     HA: μ > 220,000State your conclusion about H0. Choose the best answer below: A. Reject HA B. Do not reject H0 C. Do not reject HA D. Reject H0 E. Cannot draw a conclusion for information given

Justine is an analyst for a sleep study center. She believes that the average adult in a certain city spends more than 7.2 hours sleeping daily. To test this claim, she selects a random sample of 63 adults from the city. The following is the data from this study: The alternative hypothesis Ha:μ>7.2. The sample mean number of hours slept per night by the 63 adults is 7.52 hours. The sample standard deviation is 1.14 hours. The test statistic is calculated as 2.23.   Using the information above and the portion of the t− table below, choose the correct p− value and interpretation for this hypothesis test.    Values for right-tail areas under the t-distribution curve   Probability 0.10 0.05 0.025 0.01 0.005 Degrees of Freedom           60 1.296 1.671 2.000 2.390 2.660 61 1.296 1.670 2.000 2.389 2.659 62 1.295 1.670 1.999 2.388 2.657 63 1.295 1.669 1.998 2.387 2.656 64 1.295 1.669 1.998 2.386 2.655 65 1.295 1.669 1.997 2.385 2.654 66 1.295 1.668 1.997 2.384 2.652…

Find the critical value t Subscript c for the confidence level c=.90. and sample size n=20.

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 popcorn manufacturer claims that the bags of popcorn the factory produces have a mean weight of 6.5 ounces. The population standard deviation is known to be 0.22 ounces. A simple random sample of 40 popcorn bags has a mean of 6.7 ounces. Assume a confidence level of α = 0.10. find the value of the statistic z using. Z =

Zappos is an online retailer based in Nevada and employs 1,300 employees. One of their competitors, Amazon.com, would like to test the hypothesis that the average age of a Zappos employee is less than 36 years old. A random sample of 22 Zappos employees was found to have an average age of 33.9 years. The standard deviation for this sample was 4.1 years. Amazon would like to set α = 0.025. The correct hypothesis statement for this hypothesis test would be A)  H0: μ = 33.9; H1: μ ≠ 33.9. B)  H0: μ = 36; H1: μ ≠ 36. C)  H0: μ ≤ 36; H1: μ > 36. D)  H0: μ ≥ 36; H1: μ < 36.

#4data: 0.06, 0.11, 0.16, 0.15, 0.14, 0.08, 0.15. Use the sample data from #4 to construct a 98% confidence interval estimate for the standard deviation of the amount nitrogen-oxide emission for all cars.