Suppose a geyser has a mean time between eruptions of 70 minutes. Let the interval of time between the eruptions be normally distributed with standard deviation 18 minutes.

(a) What is the probability that a randomly selected time interval between eruptions is longer than 79 minutes?

(Round to four decimal places as needed.)

(b) What is the probability that a random sample of 88 time intervals between eruptions has a mean longer than 79 minutes?

(Round to four decimal places as needed.)

(c) What is the probability that a random sample of 27 time intervals between eruptions has a mean longer than 79 minutes?

(Round to four decimal places as needed.)

Question

Antoine

16 June, 15:20

+5

Answers (1)

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Malakai Becker · Answer 1

P (x > 83) = P (z > 9/20) = normalcdf (9/20,100) = 0.3264