The diameter of a brand of tennis balls is approximately normally distributed, with a mean of 2.63

Question:

The diameter of a brand of tennis balls is approximately normally distributed, with a mean of 2.63 inches and a standard deviation of 0.03 inch. If you select a random sample of 9 tennis balls,
a. What is the sampling of the mean?
b. What is the probability that the sample mean is less than 2.61 inches?
c. What is the probability that the sample mean is between 2.62 and 2.64 inches?
d. The probability is 60% that the sample mean will be between what two values symmetrically distributed around the population mean? Distribution
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