Question

A bag contains 10 marbles: 4 are green, 4 are red, and 2 are blue. Heather chooses a marble at random, and without putting it back, chooses another one at random. What is the probability that both marbles she chooses are blue? Write your answer as a fraction in simplest form.

Answer 1

Probability of both marbles blue
= 2/10 × 1/9
= 1/45

Answer 2

Hence there are 2 blue marbles: P = E/S = 2/10 + 1/9 = 28/90 = 0.3111111