The expected value of a random variable X is 140 and the standard deviation is 14. The expected value of the random variable Y

Complete question :

The expected value of a random variable X is 140 and the standard deviation is 14. The standard deviation of the random variable Y=3X-10 is:

42

Step-by-step explanation:

Standard deviation of Y = 3X - 10

The variance of Y

Var(Y) = Var(3X - 10)

Var(Y) = Var(3X) - Var(10)

10 is a constant :

Var(10) = 0

Hence,

Var(Y) = Var(3x)

SD(Y) = Var(Y) = Var(3X)

SD(Y) = SD(3X)

SD(Y) = 3SD(X)

SD(X) = 14

SD(Y) = 3 * 14

SD(Y) = 42

i think the length is 12 and the width is 17

$3,200 x 7.25% = $3,200 x .0725 = $232 interest monthly

$232 monthly x 12 annual = $2, 784

step-by-step explanation: