discrete random variables

Which of the follow statements is true? A. μ_(aX+b)=μ_(bX+a) B. μ_aX=μ_x+a C. μ_(X+b)=μ_X+b

C.

true or false: If X is a random variable with standard deviation 15, then the standard deviation of 2X is 30.

true

If X and Y are random variables with uX = 5 and uY = 8, then what is u2X-3Y? a) -34 b) -14 c) 14 d) 34

b.

Suppose X is always -3. Then σ_X^2= ____. A. -3 B. 9 C. 0 D. None of the above.

c

If X and Y are random variables with uX = 2 and uY = 8, then what is u2X+3Y? a) 34 b) 13 c) 28 d) 40

c.

true or false: Suppose X has a distribution with mean 10 and Y has a distribution with mean 20. The mean of X - Y is 30.

false

true or false: The number of accidents that occur at a certain intersection in a given year is a continuous random variable.

false

true or false: σ_(X-Y)^2=σ_X^2-σ_Y^2 if X and Y are independent.

false

true or false:μ_X always equals x ̅.

false

true or false: If Corr (X, Y) = 0 (i.e. ρ = 0), then X and Y are independent.

false

true or false: Let X be the temperature of an oven in degrees Fahrenheit. The variance of X is also expressed in degrees Fahrenheit but the standard deviation is not.

false

true or false: Suppose the variance of X equals 3 and the variance of Y equals 2. Suppose also that X and Y are independent. Then the variance of X - Y equals 3 + 2 = 5.

true

true or false: The number of injuries sustained by an entire football team during a typical college football game is a discrete random variable.

true

Which of the following statements is always true? A. μ_(X+Y)=μ_X+μ_Y B. μ_XY=μ_x*μ_Y C. σ_(X+Y)^2=σ_X^2+σ_Y^2 D. All of the above are always true.

a

Which of the following is a NOT a discrete random variable? a) The time between accidents on a busy highway. b) The number of accidents on a busy highway. c) The number of red cars that go by, in a random sample of 100. d) All of the above are discrete random variables.

a.