Question

There are 6 red marbles, 5 green marbles, and 4 yellow marbles in a bag. If Joe picks 2 marbles one after the other without replacement, then what is the probability that both are red in color? P(R,R)

Pilihan jawaban
2/5
1/21
5/35
1/7

Answer 1

1/7

Explanation:

6 + 5 + 4 = 15

There are 15 marbles to start with.

p(event) = (number of desired outcomes)/(total number of outcomes)

First pick (there are 6 desired outcomes out of a total of 15 possible outcomes):

p(r) = 6/15

Now there are 5 red marbles left and a total of 14 marbles left.

Second pick (there are 5 desired outcomes out of a total of 14 possible outcomes):

p(r) = 5/14

These events are independent, so we multiply the two probabilities.

p(r, r) = 6/15 × 5/14

p(r, r) = 3/7 × 1/3

p(r, r) = 1/7