Question

A bag contains 4 red marbles and 5 blue marbles. If two marbles are chosen at random, one at a time and without replacement, what is the probability of getting two red marbles?

Answer 1

$|\Omega|=9\cdot8=72\\ |A|=4\cdot3=12\\\\ P(A)=\dfrac{12}{72}=\dfrac{1}{6}\approx17\%$