sebastianzx6r

October 31st 2005, 07:10 PM

I'm having trouble with a couple of problems.

Let a chip be taken at random from a bowl that contains 6 white chips, 3 red chips, and 1 blue chip. Let the random variable X = 1 if the outcome is a white chip; let X = 5 if the outcome is a red chip; and let X = 10 if the outcome is a blue chip.

a. Find the p.m.f. of X

b. Find the mean and standard deviation of X.

For a I need a function where you can plug in X=1 and get 6/10, X=5 and get 3/10, etc..

Once I have that I can find the mean and standard deviation. I've been trying to figure out that equation.

I have (x^2+5)/10x

It gives the correct x and y values for the 1st 2 x's but not the 3rd.

Also

Suppose X is a random variable such that E(X+4)=10 and E((X+4)^2)=116

How do I find the mean and variance?

Any help would greatly be appreciated.

Thanks

Let a chip be taken at random from a bowl that contains 6 white chips, 3 red chips, and 1 blue chip. Let the random variable X = 1 if the outcome is a white chip; let X = 5 if the outcome is a red chip; and let X = 10 if the outcome is a blue chip.

a. Find the p.m.f. of X

b. Find the mean and standard deviation of X.

For a I need a function where you can plug in X=1 and get 6/10, X=5 and get 3/10, etc..

Once I have that I can find the mean and standard deviation. I've been trying to figure out that equation.

I have (x^2+5)/10x

It gives the correct x and y values for the 1st 2 x's but not the 3rd.

Also

Suppose X is a random variable such that E(X+4)=10 and E((X+4)^2)=116

How do I find the mean and variance?

Any help would greatly be appreciated.

Thanks