Statistics

Statistics

A.4 Homework Set: Normal Probability Distributions

1. Find the area under the normal distribution curve:

2.

(0 ≤ < 0.56 )

3.

( > 0.23)

4.

( ≤ −1.92)

5.

(−1.43 > )

6. What percentage of the area under the normal distribution curve falls within one standard deviation above and below the mean? Two standard deviations? Three standard deviations?

7. A survey found that people keep their television sets an average of 4.8 years. The standard deviation is 0.89 year. If a person decides to buy a new TV set, find the probability that he or she has owned the old set for the following amount of time. Assume the variable is normally distributed. a. Less than 2.5 years

b. Between 3 and 4 years

c. More than 4.2 years

Answer key is found on page 86.

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