Question

A bag contains {6} red marbles, {5} yellow marbles, and {7} green marbles. How many additional red marbles must be added to the {18} marbles alredy in the bag so that the probability of randomly drawing a red marble is {3/5}?

Answer 1

`(6 + r)/(18 + r) = (3)/(5)`

`5(6 + r) = 3(18 + r)`

`30 + 5r = 54 + 3r`

`2r = 24`

`r = 12`

12 additional red marbles should be added to the 18 marbles already in the bag.