Use the Following Information for Questions:
a Manufacturer of Cell

Multiple Choice

Use the following information for questions:
A manufacturer of cell phones is interested in evaluating two alternative existing layout and flow path designs. Design 1 is the current one in use and Design 2 is a new proposed plan. Both designs were implemented for eight consecutive working days and the output of each design was recorded.
-Suppose the sample mean difference in output (Design 2 - Design 1) was -174 phones and the standard error of the mean difference was 28. What is the 95% confidence interval for the population mean difference in output?

A) -174 $\pm$ 2.36×28
B) -174 $\pm$ 2.36× $\frac{28}{\sqrt{8}}$
C) -174 $\pm$ 28
D) -174 $\pm$ 0.95×28