A random sample of 54 students from a college are selected from a normal population with mu equal to 20 and sigma equal to 5. After a treatment is administered to the students, the researcher calculated the sample mean to be 21. Is there enough evidence to conclude that the treatment had a significant effect at the 5% significance level?  How many tails does this test have

Do people walk faster in an airport when they are departing (getting on a plane) or after they have arrived (getting off a plane)? An interested passenger watched a random sample of people departing and a random sample of people arriving and measured the walking speed (in feet per minute) of each. A hypothesis test is to be performed to determine if the mean walking speed is different between departing and arriving passengers at an airport. Suppose the p-value is 0.14. What is an appropriate conclusion? Choose the correct answer below. O A. There is sufficient evidence at the 5% significance level to indicate that the mean walking speeds for arriving and departing passengers are the same. B. There is not sufficient evidence at the 5% significance level to indicate that the mean walking speeds for arriving and departing passengers are different. C. There is not sufficient evidence at the 5% significance level to indicate that the mean walking speeds for arriving and departing passengers…

Two samples. each with n = 5 scores, have a pooled variance of 40. What is the estimated standard error for the sample mean uniference? how do i solve?

Citrus Rental is a popular car rental agency that has a history of having too few cars available, so that its available cars are overdriven. The mean monthly mileage over the years for Citrus cars has been about  1550  miles per month. Recently, though, Citrus purchased thousands of new cars, and the company claims that the average mileage of its cars is now less than in the past. To test this, a random sample of  19  recent mileages of Citrus cars was taken. The mean of these  19  mileages was  1532  miles per month, and the standard deviation was  208  miles per month.   Assume that the population of recent monthly mileages of Citrus cars is normally distributed. At the  0.1  level of significance, can it be concluded that the mean recent monthly mileage,  μ , of Citrus cars is less than  1550  miles per month?   Perform a one-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places and round your answers as…