10 years ago, of the residents of Federhon used public transportation on a regular basis; currently, do. If the number of residents who use public transportation is 60% higher than it was 10 years ago, by what percent has the number of residents of Federhon increased in the past 10 years?
Answer Choices
Correct answer marked belowSee the full step-by-step explanation
You can see the correct answer above. Sign in for free to unlock the complete worked solution.
Track your performance and improve
Get detailed analytics, unlock full explanations, and move up difficulty tiers as you practice.
Unlock the full explanation
Create a free account to reveal the correct answer, see the step-by-step explanation, and start tracking your GMAT progress.
Wait, I'm confused about the setup. If residents increased, how do we know the old total? I keep trying to solve for two unknowns.
That one equation thing is what I missed. I was trying to find actual numbers instead of using a variable.
Got 44% but took me way too long. The 60% higher wording always makes me second-guess whether to multiply by 1.6 or 0.6.
Honestly the trap is the answer choices being close together, so a small setup error kills you.
Nice one. Plugging 100 for the old population makes the algebra disappear: 60 old riders, 96 new riders, 96 = 2/3 of new total, so new total is 144.
That's clean. I used P and got (1.6 * 0.6P)/(2/3) = 1.44P.
Is this really 605-655? The percentages are easy but translating the sentence correctly is the hard part for me.
Yeah, I got it eventually but I'd probably see this as a 650+ on test day.
What it tests
Your ability to compute percentage change, percentage of a whole, and to work backwards from a final value.
Common trap
Treating successive percentage changes as additive — a 10% rise then a 10% fall is not back to the start.