The probability that both marbles she chooses are blue is 2/15
Given : A bag contains 10 marbles: 4 are green, 2 are red, and 4 are blue. Christine chooses a marble at random, and without putting it back, chooses another one at random.
To find : What is the probability that both marbles she chooses are blue?
Solution :
Total number of marbles = 10
Green marbles = 4
Red marbles = 2
Blue marbles = 4
Probability is favorable outcome upon total number of outcomes.
Probability of getting first marble is blue.
P (first blue marble) = 4/10 = 2/5
Without replacement,
i.e. Blue marble left = 3
Total marble left = 9
Probability of getting second marble is blue.
P (second blue marble) = 3/9 =1/3
The probability that both marbles she chooses are blue is
P (both blue marbles) = 2/5 x 1/3
P (both blue marbles) = 2/15
