The time taken by an automobile mechanic to finish an oil change is random with mean 29.5 minutes and standard deviation 4 minutes.

1. What is the probability that 50 oil changes take more than 1500 minutes?
2. What is the probability that a mechanic can complete 80 or more oil changes in 40 hours?
3. The mechanic wants to reduce the mean time per oil change so that the probability is 0.97 that 80 or more oil changes can be completed in 40 hours. What does the mean time need to be? Assume the standard deviation remains 4 minutes.