I need help with these three questions today please:

1) Assume that the hourly cost to operate a commercial airplane follows the normal distribution with a mean of $5,957 per hour and a standard deviation of $288.

What is the operating cost for the lowest 4% of the airplanes? (round z value to 2 decimal places and round final answer to nearest whole dollar.)

2) A study of long-distance phone calls made from General Electric Corporate Headquarters in Fairfield, Connecticut, revealed the length of calls, in minutes, follows the normal probability distribution. The mean length of time per call was 5.00 minutes and the standard deviation was 0.40 minutes.

a. What fraction of the calls between 5.00 and 5.80 minutes?(round z-score computation to 2 decimal places and round final answer to 4 decimal places.)

b. What fraction of the calls last more than 5.80 minutes?(round z-score computation to 2 decimal places and round final answer to 4 decimal places.)

c. What fraction of the calls last between 5.80 than 6.50 minutes?(round z-score computation to 2 decimal places and round final answer to 4 decimal places.)

d. What fraction of the calls last between 4.50 and 6.50 minutes?(round z-score computation to 2 decimal places and round final answer to 4 decimal places.)

e. As part of her report to the president, the director of communications would like to report the length of the longest (in duration) 6 percent of the calls. What is the time? (round z-score computation to 2 decimal places and round final answer to 2 decimal places.)

3) The mean age at which men in the United States marry for the first time follows the normal distribution with a mean of 24.7 years. The standard deviation of the distribution is 2.5 years.

For a random sample of 55 men, what is the likelihood that the age at which they were married for the first time is less than 25 years? (round z value to 2 decimal places. round your answer to 4 decimal places.)

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please show me the work and calculation so I can understand how to do it for next time.

Thanks.