The Amount of Money That Maria Earns in a Week

Multiple Choice

The amount of money that Maria earns in a week is a random variable,X,with a mean of $800 and a standard deviation of $20.The amount of money that Daniel earns in a week is a random variable,Y,with a mean of $900 and a standard deviation of $30.
The total,X +Y,of Maria's weekly income and Daniel's weekly income is a random variable with a mean of $800 + $900 = $1700 and a standard deviation of
≈ $36.
The calculation of the standard deviation requires the assumption that the incomes are independent of one another.Which of the following examples describes a situation in which that assumption may be violated?
A: Maria and Daniel are married to each other
B: Maria and Daniel work for the same company
C: Maria and Daniel work in the same business
D: Maria and Daniel were born in the same year

A) A and B
B) A,B,C,and D
C) B,C,and D
D) B and C
E) A,B,and C