1. Suppose that the speed at which cars go on the freeway is normally distributed with mean 65 mph and standard deviation 8 miles per hour. Let X be the speed for a randomly selected car. Round all answers to 4 decimal places where possible.

a. What is the distribution of X? X ~ N( ( ),( ))

b. If one car is randomly chosen, find the probability that it is traveling more than 61 mph.( )

c. If one of the cars is randomly chosen, find the probability that it is traveling between 68 and 72 mph.( )

d. 80% of all cars travel at least how fast on the freeway? ( )mph.

2. The number of secondsXafter the minute that class ends is uniformly distributed between 0 and 60. Round all answers to 4 decimal places where possible.

a. What is the distribution ofX?X~ U( ( ) ,( ))

then the sampling distribution is

b. Suppose that 35 classes are clocked.What is the distribution ofx for this group of classes?xx~ N( ( ),( ) )

c. What is the probability that the average of 35 classes will end with the second hand between 26 and 35 seconds?( )