Question

To estimate the mean pregnancy length for the population of all smokers, the researchers find a 95% confidence interval based on the sample mean of 260 days.

Option 1: Contribution margin ratio / fixed expenses
Option 2: Fixed expenses / contribution margin per unit
Option 3: Fixed expenses / contribution margin ratio
Option 4: Contribution margin per unit / fixed expenses

Answer 1

To estimate the mean pregnancy length for the population of smokers, the researchers would calculate the margin of error and use it to determine the lower and upper bounds of the 95% confidence interval.

Step-by-step explanation:

The question is asking about estimating the mean pregnancy length for the population of smokers using a 95% confidence interval based on a sample mean of 260 days.

To estimate the mean pregnancy length, the researchers would calculate the margin of error for the sample mean. The margin of error is determined by multiplying the standard deviation by the critical value for a 95% confidence interval.

The formula for calculating the margin of error is: Margin of Error = Critical Value * Standard Deviation / Square Root of Sample Size.

Once the margin of error is calculated, it is used to determine the lower and upper bounds of the confidence interval. The lower bound is the sample mean minus the margin of error, and the upper bound is the sample mean plus the margin of error.