I'm having trouble with figuring out how to solve problems similar to the one below:
Suppose the proportion of marbles that we get is as follows: 2 red, 2 green, 1 yellow and 1 blue. What is the probability that we'll get 3 red marbles out of 5?
To get the probability, I tried to find the binomial probability:
n = 5, r = 3, p = 0.4, q = 0.6
5!/3!2! x 0.4^3 x 0.6^2 = 0.2304
I'm told though that .2304 is not the right answer but I'm not sure why this is.
Can anyone guide me to the right direction (is it really incorrect?)?