A Simple Random Sample of Kitchen Toasters Is to Be $\sigma = 28 \text { hours. }$

question 20

Multiple Choice

A simple random sample of kitchen toasters is to be taken to determine the mean operational lifetime in hours. Assume that the lifetimes are normally distributed with population standard deviation $\sigma = 28 \text { hours. }$
Find the sample size needed so that a 95 % confidence interval for the mean lifetime will have a margin of error of 4 .

• A) 2
• B) 385
• C) 189
• D) 14

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Definitions:

Action Potential

Change in membrane potential in an excitable tissue that acts as an electric signal and is propagated in an all-or-none fashion.

Atria Contract

refers to the phase in the cardiac cycle when the atria (upper chambers of the heart) contract to push blood into the ventricles.

Plateau Phase

Prolongation of the depolarization phase of a cardiac muscle cell membrane; results in a prolonged refractory period.

Cardiac Muscle Cell

Cardiac muscle cell, also known as a cardiomyocyte, is a specialized type of muscle cell found in the heart that contracts to pump blood throughout the body.