BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Time, Speed, and Distance

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 53
Joined: Wed May 28, 2014 9:36 pm
Followed by:1 members

Time, Speed, and Distance

by datonman » Wed Feb 04, 2015 10:50 am
Hello,

Sultan walks at 14km/hr instead of 10km/hr, in which he would have walked 20km more. The actual distance traveled by him is what:

In this question the time is constant.
Top
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
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

by Brent@GMATPrepNow » Wed Feb 04, 2015 11:11 am
datonman wrote:Hello,

Sultan walks at 14km/hr instead of 10km/hr, in which he would have walked 20km more. The actual distance traveled by him is what:

In this question the time is constant.
Sultan walks at 14km/hr instead of 10km/hr....
At this FASTER speed, Sultan walks an ADDITIONAL 4 km every hour [14km per hour - 10km per hour = 4km per hour]

....in which he would have walked 20km more
So, Sultan walked an ADDITIONAL 20 km

Time = distance/speed
= 20/4
= 5 hours

So, Sultan walked for a total of 5 hours.

The actual distance traveled by him is what?
Sultan walked at a speed of 14 km/hr
Sultan walked for 5 hours
Distance = (speed)(time)
= (14)(5)
= 70 km


Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
User avatar
Legendary Member
Posts: 2663
Joined: Wed Jan 14, 2015 8:25 am
Location: Boston, MA
Thanked: 1153 times
Followed by:128 members
GMAT Score:770

by DavidG@VeritasPrep » Wed Feb 04, 2015 11:12 am
Hi, Datonman.

Do you mean that Sultan walked at 14km/hour for, say, T hours, and ended up going 20 km farther than he would have gone had he been walking at 10km/hour for that same T hours?

If so, the distance he'd cover walking at 14km/hour for T hours would be 14T. (R*T = D)

The distance he would have covered walking at 10km/hour for T hours would have been 10T.

We know that the distance he walked at 14 km/hour is 20 more than it would have been had he walked at 10km/hour. So we know that
14T = 10T + 20
4T = 20
T = 5.

If he walked for 5 hours, then he walked 14*5 = 70 km at 14km/hour and would have walked 10*5 = 50 at 10km/hour.
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course
Top

GMAT/MBA Expert

User avatar
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

by Brent@GMATPrepNow » Wed Feb 04, 2015 11:43 am
David brings up a good point. The question is somewhat ambiguous.

I assumed that, at 14kmh, that Sultan walked 20km FARTHER than he would have walked at 10kmh.
Is that the correct interpretation?
Or is that that the Sultan walked 10kmh and would have walked 20km FARTHER if he had walked at 14kmh?

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
User avatar
Legendary Member
Posts: 1100
Joined: Sat May 10, 2014 11:34 pm
Location: New Delhi, India
Thanked: 205 times
Followed by:24 members

by GMATinsight » Thu Feb 05, 2015 10:26 am
datonman wrote:Hello,

Sultan walks at 14km/hr instead of 10km/hr, in which he would have walked 20km more. The actual distance traveled by him is what:

In this question the time is constant.
Considering the question as
"Sultan covers a distance that is 20 km more if he walks as 14Km/Hr instead of walking at 10 Km/Hr for the same time. Find the distance covered by Sultan when he walked at 10 Km/Hr.."

Distance = Speed x Time

for Constant TIME

D1 / S1 = D2 / S2

[Let, d is the distance covered at speed 10km/hr and (d+20) is the distance covered at 14 km/hr in same time]

d/10 = (d+20)/14
i.e. 14d = 10d + 200
i.e. 4d = 200
i.e. d = 50
"GMATinsight"Bhoopendra Singh & Sushma Jha
Most Comprehensive and Affordable Video Course 2000+ CONCEPT Videos and Video Solutions
Whatsapp/Mobile: +91-9999687183 l [email protected]
Contact for One-on-One FREE ONLINE DEMO Class Call/e-mail
Most Efficient and affordable One-On-One Private tutoring fee - US$40-50 per hour
Top
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Mon Feb 09, 2015 12:01 am
If you assume the modifier is placed correctly and the verb tenses are correct -- a generous assumption, given the standards of grammar on display in the prompt -- then the question is something like:

"If Sultan had walked at 10km/hr, he would've walked 20 kilometers further than he did at 14km/hr. How far did he walk, in kilometers?"

The intent seems to be that he spent the same amount of TIME in each hypothetical trip, but would've walked further in the 10km/hr trip due to the slower speed.

This gives us two equations:

10km/trip
R = 10
T = t
D = 10t

14km/trip
R = 14
T = t
D = 14t

We're told that the first trip is 20km longer, so 10t = 14t + 20, which reduces to -4t = 20, or t = -5. So Sultan has wandered into a wormhole, traveled for -5 hours back in time, and saved himself a 20 kilometer slog. Good for him! :D
Top
Post new topic Post Reply
• Page 1 of 1