The Amount of Money That Maria Earns in a Week

question 84

Multiple Choice

The amount of money that Maria earns in a week is a random variable,X,with a mean of $900 and a standard deviation of
.The amount of money that Daniel earns in a week is a random variable,Y,with a mean of $800 and a standard deviation of
.The difference,X - Y,between Maria's weekly income and Daniel's weekly income is a random variable with a mean of $900 - $800 = $100.If the incomes are independent of one another,which of the following shows the correct method for calculating the standard deviation of the random variable X - Y?

• A)SD(X -
• Y)= Var(X -
• Y)= Var(
• X)+ Var(
• Y)= +
• B)SD(X -
• Y)= = =
• C)SD(X -
• Y)= SD(
• X)+ SD(
• Y)= +
• D)SD(X -
• Y)= SD(
• X)- SD(
• Y)= -
• E)SD(X -
• Y)= = =

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Definitions:

Monthly Dollar Sales

The total revenue generated from sales in a particular month, measured in dollars.

Unit Variable Cost

The variable cost incurred to produce one unit of product, including direct materials, direct labor, and variable manufacturing overhead.

Monthly Sales

The total revenue generated from the sales of products or services within a month.

Net Operating Income

A measure of a company's profitability from its regular business operations, excluding income and expenses from unusual or non-operational activities.