A manufacturer of paper used for packaging requires a minimum strength of 1400 g/cmz. To check on the quality of the paper, a random sample of 10 pieces of paper is selected each hour from the previous hour' s production and a strength measurement is recorded for each. The standard deviation 0 of the strength measurements, computed by pooling the sum of squares of deviations of many samples, is known to equal 140 g/cmz, and the strength measurements are normally distributed. a) What is the approximate sampling distribution of the sample mean of n = 10 test pieces of paper