Bunuel wrote:
If Juan takes 11 seconds to run y yards, how many seconds will it take him to run x yards at the same rate?
(A) 11x/y
(B) 11y/x
(C) x/(11y)
(D) 11/(xy)
(E) xy/11
Let's solve the question using the
input-output approach.
For example, let's let y =
22This means that Juan takes 11 seconds to run
22 yards, which means his speed is 2 yards per second.
From here, if we let x =
10, then the question is asking,"how many seconds will it take Juan to run 10 yards at the same rate (of 2 yards per second)?"
Well, at that speed, it will take Juan
5 seconds to run
10 yards.
In other words, if we INPUT y =
22 and x =
10, then the answer (the OUTPUT) to the question is
5.
Now we'll plug y =
22 and x =
10 into the answer choices and see which one yields the OUTPUT of
5 (A) 11x/y = (11)(
10)/22 =
5 GREAT!
(B) 11y/x = (11)(
22)/
10 =
something other than 5 ELIMINATE B
(C) x/11y = (
10)/(11)(
22) =
something other than 5 ELIMINATE C
(D) 11/xy (11)/(
10)(
22) =
1/20 ELIMINATE D
(E) xy/11 = (
10)(
22)/(11) =
20 ELIMINATE E
Answer: A
Cheers,
Brent
_________________
Brent Hanneson – Creator of gmatprepnow.com
Before you spend another second preparing for the GMAT, check out my article series, Are you doing it wrong?.
You’ll learn what the GMAT actually tests, and why memorizing a ton of formulas actually makes you less effective.