Betty picks 4 random marbles from a bowl containing 3 white, 4 yellow, and 5 blue marbles. the probability that exactly 1 of the 4 marbles drawn is blue is . the probability that at least 1 of the 4 marbles drawn is white is .

There are 12 marbles in total in the bowl.
From this bowl, we will choose 4 marbles at random.
That's 12C4 or (12*11*10*9) or 11,880 ways

Out of this, what is the probability that there is exactly 1 blue marble.
There are 5 blue balls but only 1 is selected, 5C1 ways
The rest except blue calls are 7, but only 3 slots are left, 7C3 ways

The probably of exactly 1 blue of 4 marbles is then 5C1*7C3/12C4 = 1050/11,880 = 0.0884 or 8.84%