# probability about american households math problem

• Jan 8th 2009, 02:06 PM
DINOCALC09
probability about american households math problem
9/10 households in America have a car. Let X denote the number among 4 randomly selected households that have a car.

A. Calculate P(X=2)

B. Calculate P(X>=2)

C. Calculate P(X<2)

I am unsure of what each point is exactly asking. I know that P stands for probability. Could someone put the inequalities into words for me so that I understand this further?
• Jan 8th 2009, 02:11 PM
nzmathman
A) is asking the probability X is exactly 2 and only 2.
B) is asking for the probability X is greater than or equal to 2, ie. X=2, 3 or 4.
C) is asking for the probability X is less than (but NOT including) 2, ie. X=0 or 1.

Use binomial distribution to find the probabilities.
• Jan 8th 2009, 02:17 PM
DINOCALC09
A. = 0.0486

B. = 0.9963

C. = 0.0037

is this correct. i think i understand. thank you. very helpful
• Jan 8th 2009, 03:12 PM
nzmathman
Yes - some quick use of my graphics calculator gives the same answers you have found. (Nod)