Question

Julia has a bag containing p blue marbles and q red marbles. The ratio of blue to red is 2:3. She adds r blue marbles. The ratio of blue to red marbles is now 2:1 . What is the ratio between p and r?

Answer 1

Okay, so we have 2p = q+r, and 2p = 3q, so 3q = q=r, then 2q = r, and 3q = 1.5r, and so 2p = 1.5 r, and p = 0.75r or p = 3r/4

Answer 2

1:3 ratio between p and r