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) 3 minutes ago car X was 1/2 mile ahead of car Y.
OA is D.
I guessed it right, based on the following calculations
For Statement 1 i used the relative speed formula i.e. relative speed is (u-v) when the 2 objects are traveling in the same direction.
Time= Distance / Speed
Time= (1 mile to cover in order to be 2 miles ahead)/|50-40|
Time= 1/10 hrs i.e. 6 mins. SUFFICIENT.
For Statement 2, I picked up on the phrase "traveling at different constant rates".
Therefore, if the car was 1/2 mile ahead 3 minutes ago (say t1=0), and is 1 mile ahead now (say t2= 3), it shall be 2 miles ahead after t3= 2*t2= 6. SUFFICIENT.
I assumed that since the variable (speed) is constant, the distance will keep doubling after every 3 mins as suggested by distance covered after t1 and t2. Am i correct?
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Car X & Y traveling in same direction
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pareekbharat86
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Brent@GMATPrepNow
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Target question: How many minutes from now will car X be 2 miles ahead of car Y?pareekbharat86 wrote: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) 3 minutes ago car X was 1/2 mile ahead of car Y.
Given: Car X is now 1 mile ahead of car Y
Statement 1: Car X is traveling at 50 miles per hour and car Y is traveling at 40 miles per hour.
Notice that we could easily duplicate this scenario in real life.
Start with Car X 1 mile ahead of car Y (given info)
Have Car X drive at 50 mph and car Y at 40mph.
Use a stopwatch to time how long it takes for Car X to be 2 miles ahead of Y.
As you can see, we have enough information to answer the target question
Since we can answer the target question with certainty, statement 1 is SUFFICIENT
Statement 2: 3 minutes ago car X was 1/2 mile ahead of car Y.
If car X is presently 1 mile ahead, we can see that car X gains 1/2 mile every 3 minutes.
At that rate, car X will gain another 1 mile in 6 minutes.
Since we can answer the target question with certainty, statement 2 is SUFFICIENT
Answer = D
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
GMAT/MBA Expert
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Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
Your solution looks good to me.pareekbharat86 wrote: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) 3 minutes ago car X was 1/2 mile ahead of car Y.
OA is D.
I guessed it right, based on the following calculations
For Statement 1 i used the relative speed formula i.e. relative speed is (u-v) when the 2 objects are traveling in the same direction.
Time= Distance / Speed
Time= (1 mile to cover in order to be 2 miles ahead)/|50-40|
Time= 1/10 hrs i.e. 6 mins. SUFFICIENT.
For Statement 2, I picked up on the phrase "traveling at different constant rates".
Therefore, if the car was 1/2 mile ahead 3 minutes ago (say t1=0), and is 1 mile ahead now (say t2= 3), it shall be 2 miles ahead after t3= 2*t2= 6. SUFFICIENT.
I assumed that since the variable (speed) is constant, the distance will keep doubling after every 3 mins as suggested by distance covered after t1 and t2. Am i correct?
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
