tried this problem but im stuck and done know what im doing wrong please help

Question

The time it takes broken arms of adults to heal is normally distributed with a mean of 53.7 days in a standard deviation of 5.2 days. Answer the following questions based on this information.

A.   One adult with a broken arm is randomly selected. Calculate the probability that the I’m needed for this person’s arm to heal is fear than 60 days.

B.   A simple random sample of 23 adults who have broken arms is taken. Calculate the probability that the average time for their arm to heal is more than 50 days.

C.    What is the number of days for a broken arm to heel that separates the lower 18% of the values from the upper 82% of the values?

Answer 1

A. Calculate the Z score of the 60 days. Then look at your Z table to see what percentage is to the left of that score. That is your probability.

B. Calculate the t score for the 50 days, given the 23 adults. Then look at your t table, with n-1 (n = 23) degrees of freedom to see what percentage of the distribution is to the right of the score. That is your probability.

C. Look at the Z table for the values that represent 18% and 82%, respectively. One is negative and one is positive. Then use the z-score formula to figure out the number of days.