1. Based on FAA estimates the average age of the fleets of the 10 largest U.S. commercial passenger carriers is 13.4 years with a standard deviation of 1.7 years. Suppose that 40 airplanes were randomly selected from the fleets of these 10 carriers and were inspected for cracks in these airplanes that are considered too large for flying. What is the probability that the average age of these 40 airplanes is at least 14 years old? Round your answer to 4 decimal places. Remember to round your z-value to two decimal places.

2.Assume that the average full time college student in the U.S. requires a total of $10,500 per year to cover the costs of tutition, books and fees with a standard deviation of $1,300. If 50 full time students are randomly sampled in the U.S., what is the probability that their total annual costs for tutition, books and fees exceed $550,000?

3.Use the same information about Jeannie in the above problem. Jeannie is known to be somewhat lax about getting to the airport in time to catch her flight. Suppose that she decides to leave her office so that she has a 96% chance of catching her flight; consequently there is a 4% chance that she will miss her flight. How many minutes before the flight leaves should she leave her office? Round your final answer to the nearest minute.

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