Example An accounting firm conducts a random sample of the accounts payable for the east and the west offices of one of its clients. From these two independent samples, the company wants to estimate the difference between the population mean values of the payables. The sample statistics obtained are as follows: Sample Mean Sample Size Sample Standard Deviation East Office (Population X) West Office (Population Y) 290 250 16 11 15 50 We do not assume that the unknown population variances are equal. Estimate the difference between the mean values of the payables for the two offices. Use a 95% confidence level.