Question

Suppose a geyser has a mean time between eruptions of 79 minutes. If the interval of time between the eruptions is normally distributed with standard deviation 20 minutes answer the following questions.

(a) What is the probability that a randomly selected time interval between eruptions is longer than 88 ?minutes?

?(b) What is the probability that a random sample of 12 time intervals between eruptions has a mean longer than 88 ?minutes?

c) What is the probability that a random sample of 26 time intervals between eruptions has a mean longer than 88 minutes?

?(d) What effect does increasing the sample size have on the? probability? Provide an explanation for this result. Choose the correct answer below.

A.) The probability increases because the variability in the sample mean increases as the sample size increases.

B.) The probability decreases because the variability in the sample mean decreases as the sample size increases.

C.) The probability increases because the variability in the sample mean decreases as the sample size increases.

D.) The probability decreases because the variability in the sample mean increases as the sample size increases.

(e) What might you conclude if a random sample of 26 time intervals between eruptions has a mean longer than 88 ?minutes? Choose the best answer below.

A.) The population may be greater than 79.

B.) The population mean must be more than 79, since the probability is so low

C.) The population mean cannot be 79, since the probabilty is so low

D.) The population mean is 79 ?minutes, and this is an example of a typical sampling

Answer 1

dear student in last part of (e) you need to correct option B more than to "must be less than 79" .