The lengths of human pregnancies are normally distributed with ? = 266 days and ? = 16 days. The area to the right of x = 280 is 0.1908.
- (a) Find the z value based on the given area = 0.1908 from the positive z score table A-2 in the back of the textbook.
- (b) Interpret the area 0.1908.
- (c) What is the minimum number of days for the top 10% of pregnant women?
- (d) What is the maximum number of days for the bottom 5% of pregnant women?
2. The drive-thru times at Tim Horton’s are normally distributed with ? = 138.5 seconds
and ? = 29 seconds.
(a) What is the probability that a randomly selected car will get through the drive-thru in less than 100 seconds?
- (b) What is the probability that a randomly selected car will spend more than 160 seconds in the drive-thru?
- (c) What proportion of cars spend between 2 and 3 minutes in the drive-thru?
- (d) Would it be unusual for a car to spend more than 3 minutes in the drive-thru? Why?
