We Are Interested in Comparing the Average Supermarket Prices of Two

question 67

Multiple Choice

We are interested in comparing the average supermarket prices of two leading colas. Our sample was taken by randomly selecting eight supermarkets and recording the price of a six-pack of each brand of cola at each supermarket. The data are shown in the following table:
$$\begin{array}{l}\begin{array} { c | c c | c } &\text { Price }\\\text { Supermarket } & \text { Brand 1 } & \text { Brand 2 } & \text { Difference } \\\hline 1 & \$ 2.25 & \$ 2.30 & \$ - 0.05 \\2 & 2.47 & 2.45 & 0.02 \\3 & 2.38 & 2.44 & - 0.06 \\4 & 2.27 & 2.29 & - 0.02 \\5 & 2.15 & 2.25 & - 0.10 \\6 & 2.25 & 2.25 & 0.00 \\7 & 2.36 & 2.42 & - 0.06 \\8 & 2.37 & 2.40 & - 0.03 \\\hline & \mathrm { x } _ { 1 } = 2.3125 & \mathrm { x } _ { 2 } = 2.3500 & \mathrm {~d} = - 0.0375 \\& \mathrm {~s} _ { 1 } = 0.1007 & \mathrm {~s} _ { 2 } = 0.0859 & \mathrm {~s} _ { \mathrm { d } } = 0.0381\end{array}\end{array}$$ If the problem above represented a paired difference, what assumptions are needed for a confidence interval for the mean difference to be valid?

• A) The population variances are equal.
• B) The population of paired differences has an approximately normal distribution.
• C) The samples were independently selected from each population.
• D) All of the above are needed.

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Definitions:

Memory Loss

The inability to remember information or events, which can be a temporary condition or a symptom of neurological diseases.

Monoamine

A category of neurotransmitter that includes serotonin, dopamine, and norepinephrine, important for regulating mood and behavior.

Norepinephrine

A neurotransmitter and hormone involved in the body’s fight or flight response, affecting attention and responding actions.

Acetylcholine

A neurotransmitter in the body that plays a major role in the functioning of the autonomic nervous system and in the communication between motor neurons and muscles.