Answer: 3/5
Step-by-step explanation:
Probability is the number of favorable outcomes divided by the total number of outcomes. In this case, there are 5+4+6, or 15, possible outcomes, because there is one selection from 15 marbles. Therefore, the probability of choosing a blue marble is 4/15, and the probability of choosing a red marble is 5/15. Add these together to get the probability of choosing a red or blue marble:
(4/15)+(5/15)=9/15
9/15 simplifies to 3/5.
