Question

Production of vinyl floor covering is a stable process. The hardness measurement of the ooring surface is normal with a standard deviation of 8. To monitor the production of a nevx crew of workers. a random sample of 18 vinyl specimens made from the crew are measured for hardness. The sample yields an average of 51. Calculate the 95% condence interval of .u A Enter the LOWER bound here (smaller of the two bounds). Round to two decimal places. Calculate the 95% condence interval of g Enter the UPPER hound here. Round to two decimal places. The engineer would like the 95% condence interval not to exceed a margin of error of 1.5 units. What is the smallest sample size needed to obtain the desired margin of error