1)Use theCumulative Normal Distribution Tableto find thez-scoresthat bound the middle90%

of the area under the standard normal curve. Enter the answers in ascending order. Round the answers to two decimal places.

Thez-scoresfor the given area are______and__________

2)A normal population has mean=60

and standard deviation =16

(a) What proportion of the population is greater than95

(b) What is the probability that a randomly chosen value will be less than80

3)Baby weights:

The weight of male babies less than2 months old in the United States is normally distributed with mean 12.5 pounds and standard deviation 5.1

pounds. Use the TI-84 Plus calculator to answer the following.

(a) What proportion of babies weigh more than14 pounds?

(b) What proportion of babies weigh less than16 pounds?

(c) What proportion of babies weigh between11and15 pounds?

(d) Is it unusual for a baby to weigh more than17pounds?

4)Baby weights:The weight of male babies less than

2months old in the United States is normally distributed with mean12.5

pounds and standard deviation5.1pounds. Use theCumulative Normal Distribution Tableto answer the following.

(a) Find the81st percentile of the baby weights.

(b) Find the18th percentile of the baby weights.

(c) Find the third quartile of the baby weights.

Round the answers to at least two decimal places.

5)Fish story:According to a report by the U.S. Fish and Wildlife Service, the mean length of six-year-old rainbow trout in the Arolik River in Alaska is479

millimeters with a standard deviation of39millimeters. Assume these lengths are normally distributed. Round the answers to at least two decimal places.

(a) Find the55th percentile of the lengths.

(b) Find the84th percentile of the lengths.

(c) Find the first quartile of the lengths.

(d) A size limit is to be put on trout that are caught. What should the size limit be so that

15%of six-year-old trout have lengths shorter than the limit?

6)Electricity bills:According to a government energy agency, the mean monthly household electricity bill in the United States in

2011was $109.54. Assume the amounts are normally distributed with standard deviation $16.00. Use the TI-84 Plus calculator to answer the following.

(a) Find the9th percentile of the bill amounts.

(b) Find the65th percentile of the bill amounts.

(c) Find the median of the bill amounts.

Round the answers to at least two decimal places.