Ch. 6.1 #7-49 odd

Therefore, a cutoff score of 93 will make a student eligible for the program.
23. Used Car Prices an automobile dealer finds that the average price of a previously owned vehicle is
$8256. He decides to sell cars that will appeal to the middle 60% of the market in terms of price. Find the
maximum and minimum prices of the cars the dealer will sell. The standard deviation is $1150, and the
variable is normally distributed.
$8256, $1150 . The middle 60% means that 30% of the area will be on either side of the mean.
The corresponding z score is found using area = 0.20.
The z scores are 0.84.
Min z * 0.84*1150 8256 $7290
Max z * 0.84*1150 8256 $9222
26. High School Competency Test a mandatory competency test for high school sophomores has a
normal distribution with a mean of 400 and a standard deviation of 100.
a) The top 3% of students receive $500. What is the minimum score you would need to receive this
award?
400, 100
10.03 0.97
z 1.88
Min z * 1.88*100 400 588
588 is minimum score to receive the award.
b) The bottom 1.5% of students must go to summer school. What is the minimum score you would need
to stay out of this group?
400, 100
For the bottom 1.5%, the area is 0.015.
z 2.17
Min z * 2.17*100 400 183
183 is the minimum score to avoid summer school.