GED Mathematical Reasoning TestQuantitative Problem Solving with Rational NumbersMedium
A gardener uses 2/3 of a bag of fertilizer for every 15 square feet of garden. If the gardener has a garden that is 60 square feet, how many bags of fertilizer will be needed?
- A8 bags
- B4 bags
- C1 1/3 bags
- D2 2/3 bags
Show answer & explanationAnswer & explanation
Correct answer: D. 2 2/3 bags
First, find how many '15 sq ft' sections are in 60 sq ft: 60 / 15 = 4 sections. Then, multiply the amount of fertilizer per section by the number of sections: (2/3 bag/section) * 4 sections = 8/3 bags. Convert to a mixed number: 2 2/3 bags.
Why the other options are wrong
- A. This would be if 2 bags were needed per 15 sq ft, not 2/3.
- B. This is the number of 15 sq ft sections, not the bags of fertilizer.
- C. This is an underestimation, possibly from incorrect division or multiplication.
Unit Rate with Fractional Quantities
To solve problems involving unit rates where quantities are fractional, first determine how many 'units' are present in the total, then multiply that number by the fractional amount required per unit.
- Find how many times the base unit (e.g., 15 sq ft) fits into the total (e.g., 60 sq ft).
- Multiply this count by the fractional rate (e.g., 2/3 bag per base unit).
- Convert improper fractions to mixed numbers for practical answers.
Memory trick: Sections first, then multiply by fractional need.