plz need help on the following
when dealing with question like this one
source advanced math forum
The only contents of a bag are 4 pens that write blue and 3 pens that write green. If 4 of those pens are chosen at random, what is the probability that 2 of the pens write blue and 2 of the pens write green?
I don 't know when to use simple probability or combination
usually permutations and combination deal with the number of ways
i am quite lost
when there is a will there is a way