A study of the amount of time it takes a mechanic to rebuild the transmission for a 2005 Chevrolet Cavalier shows that the mean is 8.4 hours and the standard deviation is 1.8 hours. If 40 mechanics are randomly selected, find the probability that their mean rebuild time exceeds 8.7 hours. a) (1pt) Define x-bar:  b) (1pt) Explain why  x-bar is normal c)  (3pts) Find the probability that their mean rebuild time exceeds 8.7 hours. 

Use the given information to find the minimum sample size required to estimate an unknown population mean μ.How many students must be randomly selected to estimate the mean weekly earnings of students at one college? We want 95% confidence that the sample mean is within $4 of the population mean, and the population standard deviation is known to be $65. (3pts)

Use the given degree of confidence and sample data to construct a confidence interval for the population mean μ. Assume that the population has a normal distribution.Construct a 98% confidence interval for the population mean, μ of the repair bill. Assume the population has a normal distribution. A study of 14 car owners showed that their average repair bill was $192 with a standard deviation of $8. Show work for the all the steps below. (2pts) Point estimate  (3pts) Critical value (round to 3 decimal places): (3pts) Margin of Error (round to 3 decimal places) : (3pts) CI (round to a whole number): (1pt) Interpretation:  

Complete your diagnostic exam below.

What is a defining characteristic of a chain drive system?

Which strand construction provides the highest resistance to fatigue?

Why are Lang Lay wire ropes preferred in certain applications?

Which type of belt drive provides positive, slip-free power transmission?

What is the primary advantage of synchronous belts compared to V-belts?

What is the main advantage of V-belt drives over flat belt drives?