Answer:
1/20
Explanation:
There are 16 marbles, 4 of them blue.
The probability of getting a blue marble on the first draw is 4/16.
Now there are 15 marbles, 3 of them blue.
The probability of getting a blue marble on the second draw is 3/15.
These are independent events, so the total probability is found by multiplying the two probabilities together: 4/16 x 3/15 = 1/20