Digital SATMath: AlgebraEasy
A baker is using a recipe that calls for 2.5 cups of flour for every 1 cup of sugar. If the baker uses 6.25 cups of flour, how many cups of sugar are needed?
- A2.5 cups
- B4.25 cups
- C3.75 cups
- D1.5 cups
Show answer & explanationAnswer & explanation
Correct answer: A. 2.5 cups
This problem involves a direct proportion. By setting up a ratio of flour to sugar and solving for the unknown sugar quantity, we can find the correct amount. The ratio of flour to sugar is 2.5:1. If 6.25 cups of flour are used, then 6.25 / 2.5 = 2.5 cups of sugar are needed.
Why the other options are wrong
- B. Incorrect. This would be if the ratio was 6.25 / 1.47.
- C. Incorrect. This would be if the ratio was 6.25 / 1.667.
- D. Incorrect. This would be if the ratio was 6.25 / 4.167.
Direct Proportion
A relationship between two quantities where their ratio is constant. If one quantity increases, the other increases proportionally.
- Can be written as y = kx, where k is the constant of proportionality.
- Used to solve problems involving scaling ingredients or comparing rates.
- The graph of a direct proportion is a straight line passing through the origin.
Memory trick: Same scale, same story, both grow or shrink proportionally.