Suppose a geyser has a mean time between eruptions of 68 minutes. If the interval of time between the eruptions is normally distributed with standard deviation 14 minutes, answer the following questions. Click here to view the standard normal distribution table (page 1).
Click here to view the standard normal distribution table (page 2).
(a) What is the probability that a randomly selected time interval between eruptions is longer than 74 minutes?
The probability that a randomly selected time interval is longer than 74 minutes is approximately I. (Round to four decimal places as needed.)
(b) What is the probability that a random sample of 13 time intervals between eruptions has a mean longer than 74 minutes?
The probability that the mean of a random sample of 13 time intervals is more than 74 minutes is approximately (Round to four decimal places as needed.)
(c) What is the probability that a random sample of 25 time intervals between eruptions has a mean longer than 74 minutes?
The probability that the mean of a random sample of 25 time intervals is more than 74 minutes is approximately (Round to four decimal places as needed.)
(d) What effect does increasing the sample size have on the probability? Provide an explanation for this result. Choose the correct answer below.
O A. The probability decreases 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.
OC. The probability increases because the variability in the sample mean increases as the sample size increases.
OD. The probability increases because the variability in the sample mean decreases as the sample size increases.
(e) What might you conclude if a random sample of 25 time intervals between eruptions has a mean longer than 74 minutes? Choose the best answer below.
O A. The population mean must be less than 68, since the probability is so low.
O B. The population mean is 68 minutes, and this is an example of a typical sampling.
OC. The population mean cannot be 68, since the probability is so low.
OD. The population mean may be greater than 68.
Click to select your answer(s).