Answer:
31%
Explanation:
the sum total of all marbles at the beginning is 8+(9+9)=26
the probability of picking a red marble at this point is p(1)=(8/26)
now 25 marbles remain, the distribution is now 8+17=25
the probability of picking a red marble at this point is p(2)=(8/25)
now 24 marbles remain, the distribution is now 8+16=24
the probability of picking a red marble at this point is p(3)=(8/24)
it follows that the remaining probabilities are for "not picking a red marble".
these probabilities are 1-p([1;2;3]).
Probabilities are multiplicative.
The probability for 3 consecutive non-red draws is then given by:
(1-8/26)*(1-8/25)*(1-8/24) = 103/325 | that's roughly 31%
not 100% sure!