Question

The are only blue cubes yellow cubes and green cubes in a bag. There are three times as many blue cubes as yellow cubes and five times as many green cubes as blue cubes. Sarah takes a random cube from the bag. What is the probability that Sarah takes a yellow cube?

Answer 1

Sure, I can help you with that.

Let's say there are $y$ yellow cubes in the bag. Since there are three times as many blue cubes as yellow cubes, there are $3y$ blue cubes. And since there are five times as many green cubes as blue cubes, there are $5(3y) = 15y$ green cubes.

The total number of cubes in the bag is $y + 3y + 15y = 19y$.

The probability that Sarah takes a yellow cube is the number of yellow cubes divided by the total number of cubes. So, the probability is $y / 19y = \boxed{\dfrac{1}{19}}$.