The amounts of time per workout an athlete uses a stairclimber are normally distributed, with a mean of 23 minutes and a standard deviation of 7 minutes. Find the probability that a randomly selected athlete uses a stairclimber for (a) less than

20 minutes, (b) between 23 and 32 minutes, and (c) more than 30 minutes.

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Part 1

(a) The probability that a randomly selected athlete uses a stairclimber for less than 20 minutes is

enter your response here.

(Round to four decimal places as needed.)

Part 2

(b) The probability that a randomly selected athlete uses a stairclimber between 23 and 32 minutes is

enter your response here.

(Round to four decimal places as needed.)

Part 3

(c) The probability that a randomly selected athlete uses a stairclimber for more than 30 minutes is enter your response here.

(Round to four decimal places as needed.)

Q 2

For the standard normal curve, find the z-score that corresponds to the 90th percentile.

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Part 1

A.

2.81

B.

1.52

C.

1.28

D.

0.28

A standardized exam's scores are normally distributed. In a recent year, the mean test score was 1529 and the standard deviation was 319. The test scores of four students selected at random are 1910, 1260, 2280, and 1430. Find the z-scores that correspond to each value and determine whether any of the values are unusual.

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Part 1

The z-score for 1910 is

enter your response here.

(Round to two decimal places as needed.)

Part 2

The z-score for 1260 is

enter your response here.

(Round to two decimal places as needed.)

Part 3

The z-score for 2280 is

enter your response here.

(Round to two decimal places as needed.)

Part 4

The z-score for 1430 is

enter your response here.

(Round to two decimal places as needed.)

Part 5

Which values, if any, are unusual? Select the correct choice below and, if necessary, fill in the answer box within your choice.

A.

The unusual value(s) is/are enter your response here. (Use a comma to separate answers as needed.)

B. None of the values are unusual.