Last visit was: 12 Dec 2024, 19:38 It is currently 12 Dec 2024, 19:38
Home
GMAT
Messages
Tests
Schools
Reviews
Social
Chat
My Profile
Close
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
Your Progress

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
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
avatar
cv3t3l1na
avatar
Joined: 22 Oct 2012
Last visit: 31 Dec 2012
Posts: 7
Own Kudos:
153
 []
Given Kudos: 1
Posts: 7
Kudos: 153
 []
Carol started from home on trip averaging 30 miles per hour. Updated on: 25 Nov 2012, 06:14
Originally posted by cv3t3l1na on 25 Nov 2012, 05:57.
Last edited by Bunuel on 25 Nov 2012, 06:14, edited 1 time in total.
Edited the question, tags and added the OA.
5
Kudos
Add Kudos
26
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

15% (low)

Question Stats:

84% (01:40) correct 16% (02:13) wrong based on 782 sessions

History

Date
Time
Result
Not Attempted Yet
Carol started from home on trip averaging 30 miles per hour. How fast must her mother drive to catch up her in 3 hours if she leaves 30 minutes after Carol?

A. 35 m.p.h
B. 39 m.p.h
C. 40 m.p.h
D. 55 m.p.h
E. 60 m.p.h

It is a simple one, but the answer i get is 36. Maybe my calculation is wrong...
ShowHide Answer
Official Answer
A
Most Helpful Reply
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 12 Dec 2024
Posts: 97,851
Own Kudos:
685,412
 []
Given Kudos: 88,255
Products:
GMAT Club Tests Forum Quiz
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 97,851
Kudos: 685,412
 []
Carol started from home on trip averaging 30 miles per hour. 25 Nov 2012, 06:18
6
Kudos
Add Kudos
9
Bookmarks
Bookmark this Post
cv3t3l1na
Carol started from home on trip averaging 30 miles per hour. How fast must her mother drive to catch up her in 3 hours if she leaves 30 minutes after Carol?

A. 35 m.p.h
B. 39 m.p.h
C. 40 m.p.h
D. 55 m.p.h
E. 60 m.p.h

It is a simple one, but the answer i get is 36. Maybe my calculation is wrong...

In 30 minutes at 30 miles per hour Carol covers 15 miles.

So, we need her mother to compensate 15 miles in 3 hours. Thus relative speed must be 15/3=5 miles per hour, which means that the speed of Carol's mother should be 30+5=35 miles per hour.

Answer: A.
User avatar
rajathpanta
User avatar
Joined: 13 Feb 2010
Last visit: 24 Apr 2015
Posts: 145
Own Kudos:
446
 []
Given Kudos: 282
Status:Prevent and prepare. Not repent and repair!!
Location: India
Concentration: Technology, General Management
Schools: AGSM '15 YLP '16 Melbourne '15 IIMC (PGPEX)
GPA: 3.75
WE:Sales (Telecommunications)
Schools: AGSM '15 YLP '16 Melbourne '15 IIMC (PGPEX)
Posts: 145
Kudos: 446
 []
Carol started from home on trip averaging 30 miles per hour. 27 Nov 2012, 03:24
13
Kudos
Add Kudos
Bookmarks
Bookmark this Post
In 3 hours carol covers 90 miles. In 3hrs 30 mins carol covers 105 miles. To cover the same distance her mother should drive at 105/3 miles/hr=35
General Discussion
avatar
chanchalkalra
avatar
Joined: 03 May 2012
Last visit: 27 Nov 2012
Posts: 5
Own Kudos:
15
 []
Given Kudos: 4
Posts: 5
Kudos: 15
 []
Carol started from home on trip averaging 30 miles per hour. 25 Nov 2012, 08:40
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Another approach

Before her Mom starts Carol has already travelled 15 miles(30/2)

Now in st hr her mom travels at

A. 35 miles/hr

1.Carol completes 45 miles in 1st hr after her mom whereas her mom travels 35 miles.

2nd hr-75(45+30) and 70(35+35)

3rd hr-105(75+30) and 105(70+35)
avatar
fukirua
avatar
Joined: 21 Oct 2012
Last visit: 13 Dec 2013
Posts: 19
Own Kudos:
76
 []
Given Kudos: 15
GMAT Date: 01-19-2013
Posts: 19
Kudos: 76
 []
Carol started from home on trip averaging 30 miles per hour. 26 Nov 2012, 18:33
4
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
I know why TC got 36mph.
It comes from the understanding "catch up in three hours".
If we assume that Carol and Mom should be equal in 3 hours after Carol leaves - than answer is 36 mph. 30*3=X*2.5
However the question says that 3-hours timer starts when Mom leaves the house - answer is 35 mph. 30*3.5=X*3
User avatar
jlgdr
User avatar
Joined: 06 Sep 2013
Last visit: 24 Jul 2015
Posts: 1,328
Own Kudos:
2,571
 []
Given Kudos: 355
Concentration: Finance
Schools: Wharton '17 (A) HBS '17 (WA$)
Schools: Wharton '17 (A) HBS '17 (WA$)
Posts: 1,328
Kudos: 2,571
 []
Carol started from home on trip averaging 30 miles per hour. 26 Nov 2013, 10:48
2
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
cv3t3l1na
Carol started from home on trip averaging 30 miles per hour. How fast must her mother drive to catch up her in 3 hours if she leaves 30 minutes after Carol?

A. 35 m.p.h
B. 39 m.p.h
C. 40 m.p.h
D. 55 m.p.h
E. 60 m.p.h

It is a simple one, but the answer i get is 36. Maybe my calculation is wrong...

In 30 minutes (1/2hr) Carol drives 15 miles.
Relative speed is x-30, x being the rate of mother.

So (x-30)(3) = 15

X =35
Answer is A

Cheers
Let the kudos rain begin!!
J :)
avatar
dansanso
avatar
Joined: 29 Aug 2016
Last visit: 05 Sep 2016
Posts: 1
Posts: 1
Kudos: 0
Carol started from home on trip averaging 30 miles per hour. 01 Sep 2016, 21:38
Kudos
Add Kudos
Bookmarks
Bookmark this Post
The point were they will meet will be the same distace and D= Time x Speed
Carol T=3 V= 30 so D= 10
Mom T=3.5 V= x D= 10 so X = (3.5)(10) = 35
avatar
FB2017
avatar
Joined: 18 Jun 2017
Last visit: 14 Sep 2017
Posts: 50
Own Kudos:
13
Given Kudos: 165
Posts: 50
Kudos: 13
Carol started from home on trip averaging 30 miles per hour. 20 Jul 2017, 00:07
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Total distant covered by Carol after his mother starts driving upto next 3 hours is 15(30mins)+30(1hr)+60(2hr)+60(3hr)=105 miles. Divide that by 3 hours (total time taken) gives 35.
Note: Mother has to drive 15 miles extra to compensate the half hour delay as stated in Problem statement.
Option A.
User avatar
longhaul123
User avatar
Joined: 03 Jul 2017
Last visit: 11 Nov 2018
Posts: 142
Own Kudos:
33
Given Kudos: 27
Status:IF YOU CAN DREAM IT, YOU CAN DO IT
Location: India
Concentration: Finance, International Business
Posts: 142
Kudos: 33
Carol started from home on trip averaging 30 miles per hour. 27 Sep 2017, 23:54
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Can someone let me know why is this method incorrect. Carol: speed is 30 mph , Time =3 hrs and the distance is 30*3=90 miles
Mother: Speed=x ,Time=2.5 hrs and distance is a constant = 90 miles
Therefore the speed is 36 mph
Why is this method incorrect??
User avatar
generis
User avatar
Senior SC Moderator
Joined: 22 May 2016
Last visit: 18 Jun 2022
Posts: 5,316
Own Kudos:
36,317
Given Kudos: 9,464
Products:
GMAT Club Tests
Expert reply
Posts: 5,316
Kudos: 36,317
Carol started from home on trip averaging 30 miles per hour. 28 Sep 2017, 16:16
Kudos
Add Kudos
Bookmarks
Bookmark this Post
longhaul123
Can someone let me know why is this method incorrect. Carol: speed is 30 mph , Time =3 hrs and the distance is 30*3=90 miles
Mother: Speed=x ,Time=2.5 hrs and distance is a constant = 90 miles
Therefore the speed is 36 mph
Why is this method incorrect??
longhaul123 , think again about distance. Carol drives for 3 hours and 30 minutes.

And if you're going to calculate distance this way, look at the post by FB2017 -- directly above yours, or the one from rajathpanta .

Hope it helps.
User avatar
JeffTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 04 Mar 2011
Last visit: 05 Jan 2024
Posts: 3,023
Own Kudos:
7,206
 []
Given Kudos: 1,646
Status:Head GMAT Instructor
Affiliations: Target Test Prep
Expert reply
Posts: 3,023
Kudos: 7,206
 []
Carol started from home on trip averaging 30 miles per hour. 03 Oct 2017, 10:06
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
cv3t3l1na
Carol started from home on trip averaging 30 miles per hour. How fast must her mother drive to catch up her in 3 hours if she leaves 30 minutes after Carol?

A. 35 m.p.h
B. 39 m.p.h
C. 40 m.p.h
D. 55 m.p.h
E. 60 m.p.h

We know that Carol’s rate is 30, and let’s let her mom’s rate = r. We know that her mom will have driven for 3 hours, and Carol will have driven for (3 + ½), or 3.5, hours when her mom catches up. Using the formula distance = rate x time, and knowing that both Carol and her mom have driven equal distances, we have:

30(3.5) = 3r

105 = 3r

35 = r
User avatar
shashankism
User avatar
Joined: 13 Mar 2017
Last visit: 09 Dec 2024
Posts: 619
Own Kudos:
624
Given Kudos: 88
Affiliations: IIT Dhanbad
Location: India
Concentration: General Management, Entrepreneurship
GPA: 3.8
WE:Engineering (Energy)
Posts: 619
Kudos: 624
Carol started from home on trip averaging 30 miles per hour. 03 Oct 2017, 22:36
Kudos
Add Kudos
Bookmarks
Bookmark this Post
cv3t3l1na
Carol started from home on trip averaging 30 miles per hour. How fast must her mother drive to catch up her in 3 hours if she leaves 30 minutes after Carol?

A. 35 m.p.h
B. 39 m.p.h
C. 40 m.p.h
D. 55 m.p.h
E. 60 m.p.h

It is a simple one, but the answer i get is 36. Maybe my calculation is wrong...

Speed of Carol = 30 mph
In 30 minutes Carol travels = 30 * (30/60) = 15 miles

Let the speed of carol's mother = V
So relative speed of Carol's mother w.r.t carol = V-30

Relative distance to be covered by Carol's mother in 3 hours = 15 miles with a relative speed of (V-30) mph

So, 15/(V-30) = 3
V = 35 mph

Answer A
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 35,799
Own Kudos:
929
Posts: 35,799
Kudos: 929
Carol started from home on trip averaging 30 miles per hour. 18 Nov 2024, 03:04
Kudos
Add Kudos
Bookmarks
Bookmark this Post
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.
Moderator:
Bunuel
Math Expert
97851 posts