Question

Suppose you have a bag of red, blue, and yellow marbles. If the probability of picking a red marble is1/6 and the probability of picking a yellow marble is 1/2, what is the probability of picking a blue marble?
1. 1/4
2.1/3
3.2/3
4.1/8

Answer 1

The probabilities of picking a red, blue, and yellow marble must be equal to 1. so

P(R)+P(Y)+P(B)=1

1/6+1/2+P(B)=1  making all terms have a common denominator of 6 we have:

1+3+6P(B)=6

4+6P(B)=6

6P(B)=2

P(B)=2/6

P(B)=1/3