rtaha2412 wrote:I am having trouble understanding and recognizing relative rates problems and when to subtract or add rates. Please advise
While on a straight road, Car X and Car Y are traveling
at different constant rates. If Car X is now 1 mile
ahead of Car Y, how many minutes from now will
Car X be 2 miles ahead of Car Y ?
(1) Car X is traveling at 50 miles per hour and Car Y
is traveling at 40 miles per hour.
(2) Three minutes ago Car X was 1/2
mile ahead of
Car Y.
Since Car X is now 1 mile ahead, and we're being asked how many minutes from now Car X will be 2 miles ahead, we need to know how long it will take Car X to travel 1 more mile than Car Y. To answer this question, we need to know the relative rates for X and Y.
Statement 1:
Tells us the rates for both cars, so we can calculate how much time will be needed for Car X to travel 1 more mile than Car Y. Sufficient. (Do not calculate the time!)
Statement 2:
3 minutes ago Car X was 1/2 mile ahead. Now -- 3 minutes later -- Car X is 1 mile ahead. So every 3 minutes, Car X travels 1/2 mile more than Car Y. Thus Car X will need 6 minutes to travel 1 more mile than Car Y. Sufficient.
The correct answer is
D.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at
[email protected].
Student Review #1
Student Review #2
Student Review #3
