The ratio of red marbles to blue marbles is 3:2, so for every two blue marbles there are three red marbles. This means that there are three red marbles for every four marbles in the bag. Therefore, if there are five marbles in the bag, there must be three red marbles and two blue marbles.
There are 6 different sides you can land on with a dice. So the probability of rolling any one side is 1/6. The probability of NOT rolling a 5 is the same thing as rolling anything except a 5. So that probability will be 5/6.
