ACT (Enhanced)MathematicsEasy
A baker uses a recipe that calls for 3 cups of flour for every 2 cups of sugar. If the baker wants to make a larger batch using 7.5 cups of flour, how many cups of sugar will be needed?
- A4 cups
- B5 cups
- C6 cups
- D7 cups
Show answer & explanationAnswer & explanation
Correct answer: B. 5 cups
Set up a proportion: (3 cups flour / 2 cups sugar) = (7.5 cups flour / x cups sugar). Cross-multiply to solve for x: 3x = 2 * 7.5, so 3x = 15, and x = 5.
Why the other options are wrong
- A. Incorrect calculation, perhaps by subtracting instead of dividing or incorrect ratio.
- C. Incorrect calculation, possibly by multiplying 7.5 by 2/3 incorrectly.
- D. Incorrect calculation, not maintaining the proportion.
Proportions
An equation stating that two ratios are equal. Used to find an unknown quantity when a relationship between two quantities is known.
- Can be written as a/b = c/d.
- Cross-multiplication (ad = bc) is a common way to solve.
- Units must be consistent across the ratios.
Memory trick: Proportions balance, like scales in a market stall.