Question

There are only blue cubes, yellow cubes and green cubes in a bag.

There are twice as many blue cubes as yellow cubes and seven times as many green cubes as blue cubes.

Billy takes at random a cube from the bag.

work out the probability that Billy takes a yellow cube. Write in simplistic form.

( Sorry if this question was already answered but I can't find it.)

Answer 1

Your answer is 1/7.

Explanation:

Let's assume there is 1 yellow cube in the bag. Because there are 2X as many blue cubes that means there are 2 blue cubes. Because there are 4X as many green cubes (I believe cubes not balls) then that means there are 4 green cubes.

Therefore:

1y + 2b + 4g = 7 total cubes

The probability that you pick out the yellow cube in 1 try would be #y/total amt = 1/7.