BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Interest

Expert replies
by Joy Shaha » Fri Nov 18, 2016 1:14 pm
Q. The annual interest rate earned by an investment increased by 10 percent
from last year to this year. If the annual interest rate earned by the
investment this year was 11 percent, what was the annual interest rate last
year?

A) 1% B) 1.1% C) 9.1% D) 10% E) 10.8%
Join the discussion
Source: — Problem Solving |

by DavidG@VeritasPrep » Fri Nov 18, 2016 2:31 pm
Joy Shaha wrote:Q. The annual interest rate earned by an investment increased by 10 percent
from last year to this year. If the annual interest rate earned by the
investment this year was 11 percent, what was the annual interest rate last
year?

A) 1% B) 1.1% C) 9.1% D) 10% E) 10.8%
Call last year's interest rate: x.
If it increased by 10%, it increased by .1x
This year's interest rate = x +.1x = 1.1x; we know this is 11 percent, so 1.1x = 11; x = 10; Answer is D
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course
Join the discussion

by Jay@ManhattanReview » Tue Jan 10, 2017 12:05 am
Joy Shaha wrote:Q. The annual interest rate earned by an investment increased by 10 percent
from last year to this year. If the annual interest rate earned by the
investment this year was 11 percent, what was the annual interest rate last
year?

A) 1% B) 1.1% C) 9.1% D) 10% E) 10.8%
Rate this year = Rate last year + 10%

=> 11% = 100% of Rate last year + 10% of Rate last year

=> 11% = 110% of Rate last year

=> Rate last year = (11/110)*100% = 10%.

Answer: D

-Jay
_________________
Manhattan Review GMAT Prep

Locations: New York | Tokyo | Manchester | Geneva | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
Join the discussion

by ceilidh.erickson » Tue Jan 10, 2017 2:28 pm
Note that this question has a classic trap! If you found yourself saying "11 - 10 = 1, so the answer is A," you fell for the trap.

Here's a rule of thumb that I give my students: There's no such thing as a ONE-MOVE answer! Any answer that you get to by doing one simple bit of arithmetic (e.g. just subtracting 2 numbers, as above) is almost certainly a trap answer. Trust your instincts if you think "hm, that was too easy." Reread the question and see if you missed something.
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
Join the discussion