Each marble bag sold by Dante's Marble Company contains 5 red marbles for every 7 green marbles. If a bag has 49 green marbles, how many red marbles does it contain?

Answer 1

Hi Cam'ron,

This is a proportion problem. You were given that each bag contains 5 red marbles for every 7 green marbles, so your first proportion is 5/7. Read this as five over seven, not as five-sevenths. Now, you want to know how many red marbles are in a bag of 49 greens. Since we know the ratio is 5/7, we can set up a proportion:

5/7=x/49 where:

x=number of red marbles in bag with 49 greens

You can then cross-multiply numerator*denominator. This gives:

5*49=7*x

Do the multiplication:

245=7x

Divide both sides by 7:

x=35

I hope this helps.