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. Round the answer to 3 decimal places.

a) (2pts)  Find the area/probability under the standard normal curve to the right of z = -1.25. Round the answer to 3 decimal places. b) (2pts) Find the z-score for which the area under the standard normal curve to its right is 0.70. Round the answer to 2 decimal places.  

Solve the problem.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 7.7 hours. Make sure to first define x-bar and check its normality before calculating the probability (5pts)Define x bar:x bar is normal because: Prob=

Provide an appropriate response.Assume that adults have IQ scores that are normally distributed with a mean of 100 and a standard deviation of 15 (as on the Wechsler test). Find the probability that a randomly selected adult has an IQ between 90 and 120 (somewhere in the range of normal to bright normal). Make sure to first define variable X before calculating the probability (4pts) Define X= Prob=

(1pt) ON YOUR PAPER,  please confirm that you have read, understood and followed the exam instructions thoroughly. Round All PROBABILITY/AREA ANSWERS to 4 decimal places.  Round z-score to 2 decimal places. SHOW WORK for all the questions on YOUR PAPERS.

5xy + 10x + 6y + 12

Write the number in scientific notation.A mountain’s peak is 17,500 feet above sea level.

Solve.A projectile is fired upward from the ground with an initial velocity of 400 feet per second. Neglecting air resistance, the height of the projectile at any time t can be described by the polynomial -16t2 + 400t. Find the height of the projectile at t = 5 seconds.

Write the number in scientific notation.A computer compiles a program in 0.0000416 seconds.

Find the product.(2x – 9)(5x + 6)