2. The results of a recent survey indicate that the average new car costs $23,000, with a standard deviation of $3,500. The price of cars is normally distributed.

Question

2.	The results of a recent survey indicate that the average new car costs $23,000, with a standard deviation of $3,500. The price of cars is normally distributed. 
a.	What is a Z score for a car with a price of $ 33,000?
9.415000
b.	What is a Z score for a car with a price of $30,000?
8.557857
c.	At what percentile rank is a car that sold for $30,000?

PsyDAG · Answer

Z = (score-mean)/SD = (33,000-23,000)/3500 = 10,000/3,500 = 2.86

Do the same for 30,000.

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the second Z score.