According to a report done by S & J Power, the mean lifetime of the light bulbs it manufactures is 54

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 41 feet. Assume the population standard deviation is 4.6 feet.The mean braking distance for Make B is 42 feet. Assume the population standard deviation is 4.4 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. Complete parts​ (a) through​ (e).   (a) Identify the claim and state Ho and Ha. What is the​ claim? A.The mean braking distance is different for the two makes of automobiles. This is the correct answer. B.The mean braking distance is the same for the two makes of automobiles. C.The mean braking distance is less for Make A automobiles than Make B automobiles. Your answer is…

The mean tar content of a simple random sample of 25 unfiltered king-size cigarettes is 21.4 mg, with a standard deviation of 3 mg. The mean tar content of a simple random sample of 25 filtered 100-mm cigarettes is 13.0 mg with a standard deviation of 3.8 mg. The accompanying table shows the data. Assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. Let population 1 be unfiltered king-size cigarettes. Complete parts (a) through (c) below. Click the icon to view the data. a. Use a 0.05 significance level to test the claim that unfiltered king-size cigarettes have a mean tar content greater than that of filtered 100-mm cigarettes. What does the result suggest about the effectiveness of cigarette filters? Identify the null and alternative hypotheses. O B. Ho: H1 =H2 O C. Ho: H1 #H2 H1: H1 =H2 O A. Ho: H1 = H2 H:H1 H2 O F. Ho: H1 = H2 H1:H1> H2 H:H1=H2 Hq: H1…

The​ quality-control manager at a compact fluorescent light bulb​ (CFL) factory needs to determine whether the mean life of a large shipment of CFLs is equal to 7,508 hours. The population standard deviation is 840 hours. A random sample of 49 light bulbs indicates a sample mean life of 7,328 hours. Let μ be the population mean. Determine the null​ hypothesis, H0​, and the alternative​ hypothesis, H1.

A random sample of 12 second-year university students enrolled in a business statistics course was drawn. At the course’s competition, each student was asked how many hours he or she spent doing homework in statistics. The data are listed below. It is known that the population standard deviation is σ = 8.0. The instructor has recommended that students devote 3 hours per week for the duration of the 12 week semester, for a total of 36 hours. Test to determine whether there is evidence that the average student spent less than the recommended amount of time. 31, 40, 26, 30, 36, 38,29, 40, 38, 30, 35, 38a. State your hypothesis.b. Do you reject the null hypothesis based on the un-standardized test?c. Draw a Z distribution curve and calculate your Z statistic value. What is your conclusion?d. Compute the p-value of the test and interpret your result.

According to a report done by S & J Power, the mean lifetime of the light bulbs it manufactures is 48 months. A researcher for a consumer advocate group tests this by selecting 22 bulbs at random. For the bulbs in the sample, the mean lifetime is 49 months. It is known that the population standard deviation of the lifetimes is 6 months. Assume that the population is normally distributed. Can we conclude, at the 0.05 level of significance, that the population mean lifetime, μ , of light bulbs made by this manufacturer differs from 48 months? Perform a two-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places, and round your responses as specified below. (If necessary, consult a list of formulas.) (a) State the null hypothesis H0 and the alternative hypothesis H1 . H0: H1: (b) Determine the type of test statistic to use.   ▼(Choose one)   (c) Find the value of the test…

In a study on the physical activity of young adults, pediatric researchers measured overall physical activity as the total number of registered movements (counts) over a period of time and then computed the number of counts per minute (cpm) for each subject. The study revealed that the overall physical activity of obese young adults has a mean of μ = 325 cpm and a standard deviation of a = 90 cpm. In a random sample of n = 100 obese young adults, consider the sample mean counts per minute, x. Click the icon to view the table of normal curve areas. a. Describe the sampling distribution of x. Find μ. Find o-. X 0-= (Type an integer or a decimal.) Describe the shape of the sampling distribution of x. ✩ OA. Skewed right OB. Approximately normal OC. Skewed left b. What is the probability that the mean overall physical activity level of the sample is between 300 and 310 cpm? P(300 ≤x≤310) = (Round to four decimal places as needed.) c. What is the probability that the mean overall physical…

Dr. Sylvester Stallone is a circadian rhythms researcher and believes sleep affects memory.  Having collected data on a large number of subjects who are getting the recommended amount of sleep, he knows the mean digit span of this population is 5.6 digits.  To test his hypothesis, he measures the digit span of 15 volunteers randomly selected from the population, after depriving them of one night’s sleep.  The results show a mean (X bar) of 4.1 and a standard deviation of (s) 1.4.        a.   What does Dr. Stallone conclude, using and alpha of 0.05 (two tailed)?         b. If appropriate, calculate the size of effect and provide an interpretation of the value?

The circumference of a particular species of tree was thought to be different depending on certain geographical factors. An SRS of 60 trees is selected in Sequoyah National Forest, where it is found that = 6 meters with a standard deviation = 3 meters. A second SRS of size 40 is independently selected in Yellowstone National Forest, and it is found that = 4 meters with a standard deviation = 2 meters. Let μ1 and μ2 represent, respectively, the true mean circumferences of this particular species of tree. Assume the standard deviations of the two populations are equal. A 95% confidence interval for μ1 – μ2 is