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) =
=
=
Correct Answer:

Verified
Correct Answer:
Verified
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