Neverslip, Inc., produces belts for industrial use. As part of its continuous process-improvement program, Neverslip has decided to monitor on-time shipments of its products. Suppose a random sample of 140 shipments was taken from shipping records for the last quarter and the shipment was recorded as being either “on time” or “late.” The results of the sample are contained in the file Neverslip.
a. Using the randomly sampled data, calculate a 90% confidence interval estimate for the true population proportion, p , for on-time shipments for Neverslip.
b. What is the margin of error for the confidence interval calculated in part a?
c. One of Neverslip’s commitments to its customers is that 95% of all shipments will arrive on time. Based on the confidence interval calculated in part a, is Neverslip meeting its on-time commitment?