1.
Seams Personal advertises on its website that 95% of customerorders are received within four working days. They performed anaudit from a random sample of 500 of the 6,000 orders received thatmonth and it shows 470 orders were received on time.
(Question) If Seams Personal customers really receive 95% oftheir orders within four working days, what is the probability thatthe proportion in the random sample of 500 orders is the same asthe proportion found in the audit sample or less?
2.
You collect a random sample of size n from a population andcalculate a 98% confidence interval. Which of the followingstrategies produces a new confidence interval with a decreasedmargin of error?
Use a 99% confidence level.  Use a 95% confidencelevel.  Decrease the sample size.  Use the sameconfidence level, but compute the interval n times. Approximately2% of these intervals will be larger.  Nothing canguarantee that you will obtain a larger margin of error. You canonly say that the chance of obtaining a larger interval is0.02.
3.
Faculty members at Lowell Place High School want to determinewhether there are enough students to have a Valentine's Day Formal.Eighty-eight of the 200 students said they would attend theValentine's Day Formal. Construct and interpret a 90% confidenceinterval for p.
The 90% confidence interval is (0.4977, 0.5023). We are 90%confident that the true proportion of students attending theValentine's Day Formal is between 49.77% and 50.23%.  The90% confidence interval is (0.3823, 0.4977). There is a 90% chancethat a randomly selected student who will attend the Valentine'sDay Formal lies between 38.23% and 49.77%. The 90% confidenceinterval is (0.4977, 0.5023). Ninety percent of all samples of thissize will yield a confidence interval of (0.4977, 0.5023). The 90%confidence interval is (0.3823, 0.4977). Ninety percent of allsamples of this size will yield a confidence interval of (0.3823,0.4977). The 90% confidence interval is (0.3823, 0.4977). We are90% confident that the true proportion of students attending theValentine's Day Formal is between 38.23% and 49.77%.
