A study of a company's practice regarding the payment of invoices revealed that an invoice was paid an average of 20 days after it was received. The standard deviation equaled five days. Assuming that the distribution is normal,what percent of the invoices were paid within 15 days of receipt?
A)15.87%
B)37.91%
C)34.13%
D)86.74%

Question

Quizplus · Accepted Answer

Using the properties of the normal distribution, we calculate the z-score for 15 days: z = (15 - 20) / 5 = -1. A z-score of -1 corresponds to the 15.87th percentile, meaning 15.87% of invoices were paid within 15 days.

A Study of a Company's Practice Regarding the Payment of Invoices