A ratio compares two amounts, but it does not tell you the actual amounts until you scale it, and that idea drives ratios, proportions, and rates questions on the SSAT Upper.
When a ratio changes because some members join or leave, the reliable method is to write each group as a multiple of one unknown, such as two k and three k, and let the change fix k. Rate problems use distance equals rate times time, and when two travelers move toward each other, their speeds add.
Wrong choices usually come from treating the ratio numbers as the real totals, or from answering with one group instead of both.
Sample questions
Pick an answer to see whether it is right — nothing is saved, and nothing needs an account.
Question 1Mid
At a music camp, the ratio of singers to instrumentalists was 5:7. After 6 instrumentalists left, the ratio became 5:6. How many students were in those two groups before the 6 instrumentalists left?
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Answer: E — 72
Let the numbers of singers and instrumentalists be 5k and 7k. After 6 instrumentalists left, 7k−65k=65, so 30k=35k−30 and k=6. The original total was 5k+7k=12k=72.
Question 2Mid
A bin contains white rice and brown rice in the ratio 3:5. After 12 cups of white rice are added, the amounts of the two kinds are equal. How many cups of rice were in the bin originally?
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Answer: E — 48
Let the original amounts be 3k and 5k. Equality after the addition gives 3k+12=5k, so k=6. The original total was 8k=48 cups.
Question 3Mid
Two kayakers start 78 miles apart and paddle toward each other at the same time. One travels at 8 miles per hour and the other at 5 miles per hour. After how many hours do they meet?
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Answer: A — 6
Their separation closes at 8+5=13 miles per hour. The meeting time is 78÷13=6 hours.
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