Parts A-D

A)On average, a student takes 130 words/minutemidway through an advanced court reporting course at the AmericanInstitute of Court Reporting. Assuming that the dictation speeds ofthe students are normally distributed and that the standarddeviation is 10 words/minute, find the probability that a studentrandomly selected from the course can take dictation at thefollowing speeds. (Round your answers to four decimal places.)

(1) more than 150 words/minute______


(2) between 100 and 150 words/minute________


(3) less than 100 words/minute_________

B)The tread lives of the Super Titan radialtires under normal driving conditions are normally distributed witha mean of 30,000 mi and a standard deviation of 5000 mi. (Roundyour answers to four decimal places.)

(1)What is the probability that a tire selected at random will havea tread life of more than 24,500 mi?_________


(2)Determine the probability that four tires selected at randomstill have useful tread lives after 24,500 mi of driving. (Assumethat the tread lives of the tires are independent of eachother.)_________

C)Let Z be the standard normalvariable. Find z if z satisfies the given value.(Round your answer to two decimal places.)

P(Z < z) = 0.1210

(1)z=_________

D)Let Z be the standard normalvariable. Find z if z satisfies the given value.(Round your answer to two decimal places.)

P(Z > z) = 0.9878

(1)z=_______