The diameter of a brand of tennis balls is approximately normally distributed. with a mean of 2.71 inches and a standard deviation of 0.05 inch. A random sample of 12 tennis balls is selected.

b. what is the probability that the sample mean is less than 2.70 inches? (round 4 decimal places)

c. What is the probability that the sample mean is between 2.69 and 2.73 inches?(round 4 decimal places)

d. the probability is 56% that the mean will be centered between what two values, symetrically distributed around the population mean (so that 28% of the area is less than the mean and 28% greater than the mean)?

The lower bound is ? inches. the upper bound is ? inches

(round to two decimal places)