We Are Interested in Comparing the Average Supermarket Prices of Two

Multiple Choice

We are interested in comparing the average supermarket prices of two leading colas in the Tampa area. Oursample was taken by randomly going to each of eight supermarkets and recording the price of a six -pack ofcola of each brand. The data are shown in the following table. Find a 98% confidence interval for the differencein mean price of brand 1 and brand 2. Assume that the paired data came from a population that is normallydistributed. $$\begin{array} { c | c c | c } \text { Supermarket } & \text { Brand 1 } & \text { Brand 2 } & \text { Difference } \\\hline 1 & \$ 2.25 & \$ 2.30 & \$ - 0.05 \\2 & 2.47 & 2.45 & 0.02 \\3 & 2.38 & 2.44 & - 0.06 \\4 & 2.27 & 2.29 & - 0.02 \\5 & 2.15 & 2.25 & - 0.10 \\6 & 2.25 & 2.25 & 0.00 \\7 & 2.36 & 2.42 & - 0.06 \\8 & 2.37 & 2.40 & - 0.03 \\\hline & \mathrm { x } _ { 1 } = 2.3125 & \mathrm { x } _ { 2 } = 2.3500 & \overline { \mathrm { d } } = - 0.0375 \\& \mathrm {~s} _ { 1 } = 0.1007 & \mathrm {~s} _ { 2 } = 0.0859 & \mathrm {~s} _ { \mathrm { d } } = 0.0381\end{array}$$

A) (-0.0779, 0.0029)
B) (-0.1768, 0.1018)
C) (-0.0846, 0.0096)
D) (-0.0722, -0.0028)