Just letter c Suppose a geyser has a mean time between eruptions of 74 minutes.
ID: 3300189 • Letter: J
Question
Just letter c
Suppose a geyser has a mean time between eruptions of 74 minutes. If the interval of time between the eruptions is normally distributed with standard deviation 14 minutes, answer the following questions. (a) What is the probability that a randomly selected time interval between eruptions is longer than 81 minutes? The probability that a randomly selected time interval is longer than 81 minutes is approximately 3085 (Round to four decimal places as needed.) (b) What is the probability that a random sample of 11 time intervals between eruptions has a mean longer than 81 minutes? The probability that the mean of a random sample of 11 time intervals is more than 81 minutes is approximately 04865 (Round to four decimal places as needed.) (c) What is the probability that a random sample of 26 time intervals between eruptions has a mean longer than 81 minutes? The probability that the mean of a random sample of 26 time intervals is more than 81 minutes is approximately (Round to four decimal places as needed.)Explanation / Answer
sol:
mean=74
stddev=14
n=samplesize=26
P(X>81)
z=x-mean/sd/sqrt(n)
=81-74/14/sqrt(26)
=7/14/sqrt(26)
z=2.55
P(Z>2.55)
need to find
P(Z.>2.55)
=1-P(Z<2.55)
=1-0.9946
=0.0054
ANSWER :0.0054
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