Where did this problem come from?
Part (a) has an answer that no one wants to crank out.
There are 700 marbles: 322 reds. 336 blues. 42 neutrals. We sample 70 of them.
a) What is the probability of only getting only blues and reds?
There are 700 marbles; we sample 70 of them.
. . There are: . possible samples.
There are 658 marbles that are red or blue; we want 70 of them.
. . There are: . samples that have only blues and/or reds.
The probability is: .
. . And the answer is: .
I'll wait in the car . . .