Car A and Car B are each traveling along the same stretch of highway

Question

Car A and Car B are each traveling along the same stretch of highway in the same direction. Car A leaves at 10:00am traveling at a constant rate of 40 miles per hour and Car B leaves at 10:30am traveling at a constant rate of 50 miles per hour. At what time will Car B be 40 miles ahead of Car A?

A. 3:30pm
B. 4:00pm
C. 4:30pm
D. 5:00pm
E. 5:30pm

A. 3:30pm
B. 4:00pm
C. 4:30pm
D. 5:00pm
E. 5:30pm

abhimahna · Accepted Answer

When Car B Starts at 10:30, Car A has already covered 20 Miles(Speed is 40 Miles per hour).

=> The gap between the two is 20 miles.

Thus, Car A and Car B will meet after time = Gap/Difference in speeds ( Difference is taken as both are travelling in the same direction)

=> Time = 20/50-40=20/10=2 Hours.

Thus, both the cars will meet after 2 hours. Now , in order to make a gap of another 40 miles, another period of time required = 40/50-10=4 hours.

Thus , a total of 2+4=6 hours is required for making Car B 40 miles ahead of Car A.

Thus, 10:30 a.m. + 6 hours = 4:30 p.m.

-- Hit Kudos if you get the answer

Divyadisha · Answer

Backsolved the question.

Let's check option C. 
At 4:30, car B is travelling for 6 hrs. and hence will travel a distance of 6*50= 300 miles

At 4:30 car A is travelling for 6.5 hrs, and will travel a distance of 6.5*40= 260 miles

Hence at 4:30 car A will be 300-260=40 miles ahead of car B

C is the answer

Kurtosis · Answer

Relative speed = 10 mph

At 10.30 car A would have traveled 20 miles

If car B has to be 40 miles ahead of car A, then it has cover the above 20 miles and be ahead by 40 miles. i.e.  Net additional distance car B has to cover = 60 miles

Time taken to complete 60 miles = 60/10 = 6 hours

Car B will be ahead of car A by 40 miles at 10.30 am + 6hrs = 4.30 pm

Answer: C

mech_bkvaghela · Answer

Let X be the total distance traveled by CAR A in (T+0.5) - Starting Half Hour earlier. 
= X=40(T+0.5)
Total distance traveled by CAR B in time T, 
= X+ 40 = 50 T

Put Value of X from eq 1 in eq 2 
= 40 (T+0.5) + 40 = 50 T
deriving 
=T= 6 Hours

Starting at 10:30 AM, At 16:30 PM (6 Hours)

Hope it helps.

mbaprep2016 · Answer

A starts at 10:00 and by the time B starts A is 20 miles ahead 
now B has to go 40 mile ahead, and b has to cover 20 miles also 
so total 60 miles 
50-40 = 10 miles/ hour relative seed ....
6 hours 10:30+6 = 4:30

Nunuboy1994 · Answer

Bunuel

Could we simply do

40 +20/ (50-40) = 6

10:30 + 6 hours?

JeffTargetTestPrep · Answer

Car A’s speed is 40 mph and it starts at 10:00 a.m., so when Car B starts at 10:30 a.m., Car B will be 40 x 1/2 = 20 miles behind Car A. To determine what time will Car B be 40 miles ahead of Car A, we can use the following formula:

change in distance/change in rate = time

The change in distance is 60 miles, since Car B needs to catch up to Car A starting from 20 miles behind and needing to be 40 miles ahead. The change in rate is 50 - 40 = 10 mph. Thus:

60/10 = 6 hours

So, Car B needs 6 hours to be 40 miles ahead of Car A. Since Car B starts at 10:30 a.m., it will be 40 miles ahead of Car A at 10:30 a.m. + 6 hours = 4:30 p.m.

Answer: C

lenric · Answer

When car B starts its trip, it's already 20 miles behind. For it to be 40 miles ahead of A, 60 miles have to be "recovered".

Since car B is 10 mph faster than A, car B will take 6 hours to "recover" the 60 miles, which will be achieved at 4:30 pm.

bumpbot · Answer

Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.

Car A and Car B are each traveling along the same stretch of highway

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

Car A and Car B are each traveling along the same stretch of highway

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards