GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 16 Oct 2019, 22:30

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Two cars start at the same point and travel in opposite directions. If

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 58390
Two cars start at the same point and travel in opposite directions. If  [#permalink]

### Show Tags

28 May 2017, 03:39
1
3
00:00

Difficulty:

5% (low)

Question Stats:

92% (00:54) correct 8% (01:31) wrong based on 147 sessions

### HideShow timer Statistics

Two cars start at the same point and travel in opposite directions. If one car travels at 45 miles per hour and the other at 60 miles per hour, how much time will pass before they are 210 miles apart?

(A) 0.5 hours
(B) 1 hour
(C) 1.5 hours
(D) 2 hours
(E) 2.5 hours

_________________
Current Student
Joined: 18 Aug 2016
Posts: 609
Concentration: Strategy, Technology
GMAT 1: 630 Q47 V29
GMAT 2: 740 Q51 V38
Re: Two cars start at the same point and travel in opposite directions. If  [#permalink]

### Show Tags

28 May 2017, 04:00
1
relative speed is 105 miles per hour and they will take 2 hrs to be 210 miles apart

Option D

Sent from my iPhone using GMAT Club Forum
_________________
We must try to achieve the best within us

Thanks
Luckisnoexcuse
Senior SC Moderator
Joined: 22 May 2016
Posts: 3549
Two cars start at the same point and travel in opposite directions. If  [#permalink]

### Show Tags

28 May 2017, 04:49
Bunuel wrote:
Two cars start at the same point and travel in opposite directions. If one car travels at 45 miles per hour and the other at 60 miles per hour, how much time will pass before they are 210 miles apart?

(A) 0.5 hours
(B) 1 hour
(C) 1.5 hours
(D) 2 hours
(E) 2.5 hours

When cars travel in opposite directions, whether away from or toward one another, add their respective rates.

45 + 60 = 105 mph

rate * time = distance --->

D/r = t

Distance is 210 miles.

210 miles / 105 mph = 2 hours
_________________
SC Butler has resumed! Get two SC questions to practice, whose links you can find by date, here.

Choose life.
Manager
Joined: 23 May 2017
Posts: 235
Concentration: Finance, Accounting
WE: Programming (Energy and Utilities)
Re: Two cars start at the same point and travel in opposite directions. If  [#permalink]

### Show Tags

28 May 2017, 05:27
2
1
Two cars start at the same point and travel in opposite directions. If one car travels at 45 miles per hour and the other at 60 miles per hour, how much time will pass before they are 210 miles apart?

There are two ways to solve this one:
{1} Find the relative speed between two cars and find the time taken: $$\frac{210}{ relative speed : 45+60}$$ = $$\frac{210}{105}$$ = 2 hours

{2} Find the relationship between the two car's speed.
for every 60 miles car 1 travels, car 2 travels 45 miles
that is : for every 4 mile car1 travels, car2 travels 3 miles

So car 1 and car 2 will cover the distance 210 miles in part : 4:3

let x be the factor for the distance travelled by car 1 and car2 : 4x + 3x = 210 ; x = 30

so car 1 drove = 4 * 30 = 120 miles
car 2 drove = 3 * 30 = 90 miles

time taken by car 1 to travel = time taken by car 2 to travel = $$\frac{120}{60}$$ = $$\frac{90}{45}$$ = 2 hours

Kudos me if you like the approach. It will give me encouragement
_________________
If you like the post, please award me Kudos!! It motivates me
Senior SC Moderator
Joined: 22 May 2016
Posts: 3549
Two cars start at the same point and travel in opposite directions. If  [#permalink]

### Show Tags

28 May 2017, 10:00
Leo8 wrote:
{1} Find the relative speed between two cars and find the time taken: $$\frac{210}{ relative speed : 45+60}$$ = $$\frac{210}{105}$$ = 2 hours

Though frequently used and technically accurate, just want to note that "relative speed" can be confusing in the context of cars moving in opposite directions (whether coming toward each other or moving away from one another). In the latter scenario, "relative" also means "combined speeds where rates are added."

(IMO "relative" makes more intuitive sense when you think of the "chase," where cars are moving in the same direction and slower rate is subtracted from faster rate.)

Quote:
Kudos me if you like the approach. It will give me encouragement

Done. Now please pay it forward.
_________________
SC Butler has resumed! Get two SC questions to practice, whose links you can find by date, here.

Choose life.
Manager
Joined: 23 May 2017
Posts: 235
Concentration: Finance, Accounting
WE: Programming (Energy and Utilities)
Re: Two cars start at the same point and travel in opposite directions. If  [#permalink]

### Show Tags

29 May 2017, 06:15
genxer123 wrote:
Leo8 wrote:
{1} Find the relative speed between two cars and find the time taken: $$\frac{210}{ relative speed : 45+60}$$ = $$\frac{210}{105}$$ = 2 hours

Though frequently used and technically accurate, just want to note that "relative speed" can be confusing in the context of cars moving in opposite directions (whether coming toward each other or moving away from one another). In the latter scenario, "relative" also means "combined speeds where rates are added."

(IMO "relative" makes more intuitive sense when you think of the "chase," where cars are moving in the same direction and slower rate is subtracted from faster rate.)

Quote:
Kudos me if you like the approach. It will give me encouragement

Done. Now please pay it forward.

genxer123
By relative speed, I meant effective speed.
I would say both Car 1 and Car 2 were spreading apart with a rate of 105 miles per hour. This speed is not the exact speed of car 1 or car 2 but the effective speed at which they are moving apart. I don't see any confusion in calling this as relative speed.

you could have a chase scenario , a crash scenario - in both the cases , it is recommended to calculate the relative speed / effective speed of the whole action.

and Thanks for the Kudos
_________________
If you like the post, please award me Kudos!! It motivates me
Verbal Forum Moderator
Status: Greatness begins beyond your comfort zone
Joined: 08 Dec 2013
Posts: 2400
Location: India
Concentration: General Management, Strategy
Schools: Kelley '20, ISB '19
GPA: 3.2
WE: Information Technology (Consulting)
Re: Two cars start at the same point and travel in opposite directions. If  [#permalink]

### Show Tags

21 Jul 2017, 10:31
Bunuel wrote:
Two cars start at the same point and travel in opposite directions. If one car travels at 45 miles per hour and the other at 60 miles per hour, how much time will pass before they are 210 miles apart?

(A) 0.5 hours
(B) 1 hour
(C) 1.5 hours
(D) 2 hours
(E) 2.5 hours

Relative speed of both cars = 45+60 = 105 miles per hour
Distance = 210 miles
Time = 210/105 = 2 hours

_________________
When everything seems to be going against you, remember that the airplane takes off against the wind, not with it. - Henry Ford
The Moment You Think About Giving Up, Think Of The Reason Why You Held On So Long
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8085
Location: United States (CA)
Re: Two cars start at the same point and travel in opposite directions. If  [#permalink]

### Show Tags

30 Jul 2017, 17:51
Bunuel wrote:
Two cars start at the same point and travel in opposite directions. If one car travels at 45 miles per hour and the other at 60 miles per hour, how much time will pass before they are 210 miles apart?

(A) 0.5 hours
(B) 1 hour
(C) 1.5 hours
(D) 2 hours
(E) 2.5 hours

Since we have a diverging rate problem, we can use the following formula:

distance of car 1 + distance of car 2 = 210

We can let t = the time traveled by either car, and thus the distance of car 1 is 45t and the distance of car 2 is 60t. Thus:

45t + 60t = 210

105t = 210

t = 2 hours

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Non-Human User
Joined: 09 Sep 2013
Posts: 13204
Re: Two cars start at the same point and travel in opposite directions. If  [#permalink]

### Show Tags

08 Oct 2018, 17:39
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: Two cars start at the same point and travel in opposite directions. If   [#permalink] 08 Oct 2018, 17:39
Display posts from previous: Sort by