Posted: November 30th, 2016

What is the lower limit of the 95% confidence interval? What is the upper limit of the 95% confidence interval?

For a study conducted by the research department of a pharmaceutical company, 245 randomly selected individuals were asked to report the amount of money they spend annually on prescription allergy relief medication. The sample mean was found to be $17.60 with a standard deviation of $5.30 . A random sample of 210 individuals was selected independently of the first sample. These individuals reported their annual spending on non-prescription allergy relief medication. The mean of the second sample was found to be $18.40 with a standard deviation of $4.40. As the sample sizes were quite large, it was assumed that the respective population standard deviations of the spending for prescription and non-prescription allergy relief medication could be estimated as the respective sample standard deviation values given above. Construct a 95% confidence interval for the difference between the mean spending on prescription allergy relief medication () and the mean spending on non-prescription allergy relief medication (). Then complete the table below.

What is the lower limit of the 95% confidence interval? What is the upper limit of the 95% confidence interval?

Carry your intermediate computations to at least three decimal places. Round your answers to at least two decimal places