Challenge Your Exam Readiness With Our Free GRE Practice Questions

Let initial green GG and white WW satisfy G:W=3:7G:W=3:7 with G+W=80G+W=80. The ratio parts sum to 3+7=103+7=10, so each part represents 80/10=880/10=8 marbles. Thus G=3⋅8=24G=3\cdot 8=24 and W=7⋅8=56W=7\cdot 8=56. We add xx green marbles; whites remain 5656. We want the new ratio (G+x):W=1:1⇒G+x=W (G+x):W = 1:1\Rightarrow G+x = W. Substitute G=24G=24: 24+x=56⇒x=3224 + x = 56 \Rightarrow x = 32. None of the options shows 32—double-check arithmetic. Recompute: W=56W=56, G=24G=24. To equalize, add 56−24=3256-24=32 greens. Since 32 is not a listed choice, ensure no misread: total 80, ratio 3:7 is correct. The required addition is indeed 32. If the closest option is 30 (C), that would not make 1:1; it would yield G′=54,W=56G'=54, W=56, still short. The mathematically correct answer is 32. If forced to choose among given options, none is correct. On the GRE, such mismatches are rare; when they occur in practice, trust the algebra and re-read the stem. The correct computation shows that 32 green marbles must be added to reach a 1:1 ratio.

(Note: The correct value is 32; options appear to contain an error.)