An engineer working on the auto assembly line is preparing to estimate the mean time required to install a dashboard. Assuming a required standard deviation of 10 seconds in the estimated mean, determine the sample size under the following conditions:
a. The desired confidence level of being in error by no more than one second (in either direction) is 0.99.
b. The desired confidence level is 0.95 for a tolerable error of one second.
c. A confidence level of 0.99 is desired with a tolerable error of two seconds. How does the sample size you obtain compare with your answer to (a)?
d. Repeat (a), assuming that σ = 20 seconds. By how much does the sample size decrease?