9. The most famous geyser in the world, Old Faithful in Yellowstone National Park, has a mean time between eruptions of 85 minutes. The interval of time between eruptions is normally distributed with a standard deviation of 21.25 minutes. What is the probability that a randomly selected time interval between eruptions is longer than 60 minutes? What is the probability that a random sample of 20 time-intervals has a mean longer than 60 minutes? What is the probability that a random sample of 30 time-intervals has a mean between 80 and 84 minutes? What is the bottom 5% of time-intervals between eruptions?

Suppose the weight of watermelons produced in Adana follows the normal distribution with mean 7.2 kg and standard deviation 2.4. Find the proportion of these watermelons that weight heavier than 7.5kg. If we randomly select one of these watermelons, find the probability that its weight will be less than 7kg.

What is the answer to part F?

Suppose speeds of vehicles traveling on a highway have an unknown distribution with mean 63 and standard deviation 4 miles per hour. A sample of size n=34 is randomly taken from the population and the mean is taken. What is the probability that the sample mean is less than 65 mph?  Do not round your answer.