Praxis Core Academic Skills for Educators: Mathematics (5733)Number and QuantityEasy
A caterer is preparing punch for an event. The recipe calls for 3 parts juice A, 2 parts juice B, and 1 part sparkling water. If the caterer needs to make a total of 90 liters of punch, how many liters of juice A are needed?
- A30 liters
- B15 liters
- C45 liters
- D60 liters
Show answer & explanationAnswer & explanation
Correct answer: C. 45 liters
First, find the total number of 'parts' in the ratio: 3 + 2 + 1 = 6 parts. Next, determine the volume of one part by dividing the total volume by the total parts: 90 liters / 6 parts = 15 liters per part. Finally, multiply the volume per part by the number of parts for juice A: 15 liters/part * 3 parts = 45 liters.
Why the other options are wrong
- A. This might be the volume of juice B.
- B. This might be the volume of one 'part'.
- D. This might result from miscalculating the total parts or the volume per part.
Ratio with Total Quantity
To find individual quantities when given a ratio and a total amount, sum the ratio parts, divide the total by this sum to find the value of one 'part', then multiply by each ratio number.
- The sum of ratio parts represents the total 'units' of the mixture.
- Divide the total quantity by the sum of parts to find the value of one part.
- Multiply the value of one part by each ratio number to find individual quantities.
Memory trick: Parts add up, total divides, then multiply for real-world sizes!