Qnt 561 Wk 4 The Payment Time Case

The Payment Time CaseNameCourseTutor’s NameDateSummaryPayment time case study applies the concepts of sampling and confidence intervals in a business problem. Stockton CA has installed a new electronic billing system designed by a consultant who claims that the billing system will reduce mean invoice payment time from 39 days or more to 19.5 days (i.e. payment time reduced by 50%). The population standard deviation of payment time is 4.2days;µ <19.5 sample size 65 invoices, Population size 7823 invoices.Test hypothesis µ <19.5, type of test one-tailed test (Atrill & McLaney, 2013). The rule in standard normal distribution curve is that, 95% of the population lies within 2 standard deviation of the mean and 99% of the population lie with 3 standard deviation of the mean. Since this is a sampling distribution the standard error is used instead of the mean. The standard error of the sample is 0.5209. Therefore the confidence intervals are Lower limit for 99% confidence interval= 19.5 - (2.576) (0.5205) = 18.16 therefore the claim by the consultant is within the confidence interval. The critical value z = 18.1077-19.5 / (4.2/√65) =