Data Sufficiency

In a serving of a breakfast cereal that contains only oats, raisins, and nuts, the ratio of oats to raisins to nuts by weight is 3 to 2 to 1, respectively. How many ounces of raisins are in the serving?

(1) The serving weighs 4 ounces.
(2) The serving contains 2 ounces of oats.

Can someone help why it is D, I thought it is A only

Lets say amounts of oats, raisins and nuts are 3x, 2x and x.

Statement 1 : 3x+2x+x = 4, we can find out x,. suff

statement 2 3x = 2, we can again find out x. suff

Answer D

anwarma wrote:In a serving of a breakfast cereal that contains only oats, raisins, and nuts, the ratio of oats to raisins to nuts by weight is 3 to 2 to 1, respectively. How many ounces of raisins are in the serving?

(1) The serving weighs 4 ounces.
(2) The serving contains 2 ounces of oats.

Can someone help why it is D, I thought it is A only

If you know the full ratio, knowing any real number will allow you to solve for everything.

(1) 3x + 2x + x = 4; we can solve for x.

(2) o:r:n=3:2:1; knowing that o = 2, we can solve for r and n.