Last year, Cedric had 35 plants in his garden. This year, the number of plants in Cedric's garden is 60%...
GMAT Problem-Solving and Data Analysis : (PS_DA) Questions
Last year, Cedric had \(\mathrm{35}\) plants in his garden. This year, the number of plants in Cedric's garden is \(\mathrm{60\%}\) greater than the number of plants in his garden last year. How many plants does Cedric have in his garden this year?
1. TRANSLATE the problem information
- Given information:
- Last year: 35 plants
- This year: 60% greater than last year
- What we need to find: Number of plants this year
2. INFER the approach
- '60% greater than 35' means we start with 35 and add 60% more
- Strategy: Find 60% of 35, then add it to the original 35
- Mathematical approach: \(35 + (60\% \times 35)\)
3. SIMPLIFY the calculations
- Convert percentage: \(60\% = 0.60\)
- Calculate the increase: \(0.60 \times 35 = 21\) plants
- Add to original: \(35 + 21 = 56\) plants
Answer: 56
Why Students Usually Falter on This Problem
Most Common Error Path:
Weak INFER skill: Students misunderstand what '60% greater' means and think it just means '60% of the original amount.'
They calculate: \(60\% \text{ of } 35 = 0.60 \times 35 = 21\) plants
They stop here and answer 21, forgetting that this is just the increase, not the total. The problem asks for the total number of plants this year, which should be the original plus the increase.
This leads to confusion and an incorrect answer of 21.
Second Most Common Error:
Poor SIMPLIFY execution: Students understand the concept correctly but make calculation errors.
They set up: \(35 + (60\% \text{ of } 35)\) but then calculate 60% of 35 incorrectly, perhaps getting \(60\% \text{ of } 35 = 18\) instead of 21, leading to a final answer of 53.
The Bottom Line:
The key challenge is understanding that '\(X\% \text{ greater than } Y\)' means \(Y + (X\% \text{ of } Y)\), not just \(X\% \text{ of } Y\). Students need to remember they're finding a new total, not just the amount of increase.