1. An experiment is conducted to determine whether a new computer program will speed up the processing of credit card billing at a large bank. The mean time to process billing using the present program is 12.3 min. with a standard deviation of 3.5 min. The new program is tested with 100 billings and yielded a sample mean of 10.9 min. Assuming the standard deviation of times in the new program is the same as the old, does the new program significantly reduce the time of processing? Use α = 0.05.
2. Another bank is experimenting with programs to direct bill companies for commercial loans. They are particularly interested in the number of errors of a billing program. To examine a particular program, a simulation of 1000 typical loans is run through the program. The simulation yielded a mean of 4.6 errors with a standard deviation of 0.5. Construct a 95% confidence interval on the true mean error rate.