Find the 90 percent confidence interval for the variance and standard deviation for the time it takes state police inspector to check a truck for safety if a sample of 27 trucks has a standard deviation of 8.9 minutes. Assume the variable is normally distributed

The speed of cars  on a specific road is normally distributed with a mean of 54 mph and a standard deviation of 3. The top 2.5% of cars are traveling at at least what mph?

Times for a surgical procedure are normally distributed. There are two methods. Method A has a mean of 35 minutes and a standard deviation of 3 minutes, while method B has a mean of 39 minutes and a standard deviation of 1.5 minutes. Which procedure is preferred if the procedure must be completed within 34 minutes? Which procedure is preferred if the procedure must be completed within 40.0 minutes? Which procedure is preferred if the procedure must be completed within 43 minutes?

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 40 feet. Assume the population standard deviation is 4.9 feet. The mean braking distance for Make B is 44 feet. Assume the population standard deviation is 4.6 feet. At a = 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). Click here to view page 1 of the standard normal distribution table. Click here to view page 2 of the standard normal distribution table. (a) Identify the claim and state H, and Ha. What is the claim? A. The mean braking distance is different for the two makes of automobiles. B. The mean braking distance is less for Make A automobiles than Make B…

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 42 feet. Assume the population standard deviation is 4.7 feet. The mean braking distance for Make B is 45 feet. Assume the population standard deviation is 4.4 feet. At a = 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) rari rz (b) Find the critical value(s) and identify the rejection region(s). The critical value(s) is/are (Round to three decimal places as needed. Use a comma to separate answers as needed.)

With a mean of 10 and standard deviation of 5. Assume that the population data are normally distributed.  Calculate the z-score for a raw score of 5. What proportion of the distribution is equal to or less than this score?

The weight of male contestants is normally distributed with a mean of 96 kg pounds and a standard deviation of 12 kg. If 35% of contestants satisfy a maximum weight requirement for police officers, what is the maximum weight requirement?

The lifetimes of a certain type of calculator battery are normally distributed. The mean lifetime is 400 days, with a standard deviation of 50 days. For a sample of 6000 new batteries, determine how many batteries will last less than 280 days.

The distribution of the student heights at a large college is approximately bell shaped. If the mean height is 66 inches,and approximately 95% of the heights fall between 32 and 100 inches, then, the standard deviation of the heightdistribution is approximately equal to

Suppose the mean number of candies in a standard vending machine bag is 47.6 with a standard deviation of 1.3 . assume that the number of candies is normally distributed what percentage of bags have less than 45 candies?