In: Statistics and Probability
An industrial sewing machine uses ball bearings that are targeted to have a diameter of 0.75 inch. The lower and upper specification limits under which the ball bearing can operate are 0.735 inch (lower) and 0.765 inch (upper). Past experience has indicated that the actual diameter of the ball bearings is approximately normally distributed, with a mean of 0.755 inch and a standard deviation of 0.006 inch. Suppose a random sample of 2121 ball bearings are selected. Complete parts (a) through (e).
a. What is the probability that the sample mean is between the target and the population mean of 0.755?
(Type an integer or decimal rounded to four decimal places as needed.)
b. What is the probability that the sample mean is between the lower specification limit and the target?
(Type an integer or decimal rounded to four decimal places as needed.)
c. What is the probability that the sample mean is greater than the upper specification limit?
(Type an integer or decimal rounded to four decimal places as needed.)
d. What is the probability that the sample mean is less than the lower specification limit?
(Type an integer or decimal rounded to four decimal places as needed.)
e. The probability is 93% that the sample mean diameter will be greater than what value?