Letter C

Suppose a geyser has a mean time between eruptions of 69 minutes. Let the interval of time between the eruptions be normally distributed with standard deviation 23 minutes. Complete parts (a) through (e) below. (a) What is the probability that a randomly selected time interval between eruptions is longer than 80 minutes? The probability that a randomly selected time interval is longer than 80 minutes is approximately 0.3162 . (Round to four decimal places as needed.) (b) What is the probability that a random sample of 9 time intervals between eruptions has a mean longer than 80 minutes? The probability that the mean of a random sample of 9 time intervals is more than 80 minutes is approximately 0.0757. (Round to four decimal places as needed.) (c) What is the probability that a random sample of 22 time intervals between eruptions has a mean longer than 80 minutes? The probability that the mean of a random sample of 22 time intervals is more than 80 minutes is approximately (Round to four decimal places as needed.)