Praxis Core Academic Skills for Educators: Mathematics (5733)Number and QuantityMedium
A chef is preparing a dish that requires 2.5 cups of broth. If the chef only has a measuring cup that measures in 1/8 cup increments, how many 1/8 cup increments of broth are needed?
- A25
- B10
- C20
- D16
Show answer & explanationAnswer & explanation
Correct answer: C. 20
First, convert 2.5 cups to a fraction: 2.5 = 5/2 cups. Then, divide the total amount of broth needed (5/2 cups) by the size of each increment (1/8 cup). (5/2) ÷ (1/8) = (5/2) * (8/1) = 40/2 = 20 increments.
Why the other options are wrong
- A. This results from multiplying 2.5 by 10, or an incorrect conversion.
- B. This results from an incorrect calculation, possibly dividing by 1/4 instead of 1/8.
- D. This would be the case if 2 cups were needed (2 * 8 = 16).
Dividing Decimals by Fractions
To divide a decimal by a fraction, first convert the decimal to a fraction. Then, apply the 'keep, change, flip' method: keep the first fraction, change division to multiplication, and flip (invert) the second fraction, then multiply.
- Convert decimal to fraction
- Keep, Change, Flip (KCF) for division of fractions
- Multiply the resulting fractions
- Simplify the final answer
Memory trick: Divide: Convert, Flip, Multiply, Simplify.