It is currently 17 Oct 2017, 01:06

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Speed Question

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Retired Moderator
User avatar
Joined: 18 Jul 2008
Posts: 962

Kudos [?]: 294 [0], given: 5

Speed Question [#permalink]

Show Tags

New post 27 Apr 2009, 15:43
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 1 sessions

HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

A 400-meter runner spent 4 more seconds on the first half of the distance than he did on the second. If the runner finished the 400-meter distance in 50 seconds, what was his average speed for the first 200 meters?

a) 24 1/3 kmh
b) 25 1/3 kmh
c) 26 2/3 kmh
d) 27 2/3 kmh
e) 29 1/12 kmh

This is a pretty easy one, but I couldn't understand this:

Answer: Denote x the time the runner spent on the first 200 meters. Then, x + (x - 4) = 50 from where x = 27 seconds

Why can't I say X+4 = first 200 meters, X = last 200 meters

Then x+4 + x = 50?

Kudos [?]: 294 [0], given: 5

Manager
Manager
User avatar
Joined: 19 Aug 2006
Posts: 239

Kudos [?]: 13 [0], given: 0

Re: Speed Question [#permalink]

Show Tags

New post 27 Apr 2009, 18:00
bigfernhead wrote:
A 400-meter runner spent 4 more seconds on the first half of the distance than he did on the second. If the runner finished the 400-meter distance in 50 seconds, what was his average speed for the first 200 meters?

a) 24 1/3 kmh
b) 25 1/3 kmh
c) 26 2/3 kmh
d) 27 2/3 kmh
e) 29 1/12 kmh

This is a pretty easy one, but I couldn't understand this:

Answer: Denote x the time the runner spent on the first 200 meters. Then, x + (x - 4) = 50 from where x = 27 seconds

Why can't I say X+4 = first 200 meters, X = last 200 meters

Then x+4 + x = 50?


There's no reason you cannot - and you will still get x=27sec for the 1st 200 meters.

x+4 - 1st 200 meters
x - the last 200 meters

x+x+4=50
2x=46
x=23

23+3=27sec

However, I seem to have a problem with calculating the final answer - is it B?

Kudos [?]: 13 [0], given: 0

Retired Moderator
User avatar
Joined: 18 Jul 2008
Posts: 962

Kudos [?]: 294 [0], given: 5

Re: Speed Question [#permalink]

Show Tags

New post 28 Apr 2009, 06:33
Thanks for the explanation.

The answer is C.

Kudos [?]: 294 [0], given: 5

Manager
Manager
User avatar
Joined: 19 Aug 2006
Posts: 239

Kudos [?]: 13 [0], given: 0

Re: Speed Question [#permalink]

Show Tags

New post 28 Apr 2009, 17:39
bigfernhead wrote:
Thanks for the explanation.

The answer is C.


Would you care to show your calculations?

Kudos [?]: 13 [0], given: 0

SVP
SVP
User avatar
Joined: 29 Aug 2007
Posts: 2472

Kudos [?]: 841 [0], given: 19

Re: Speed Question [#permalink]

Show Tags

New post 28 Apr 2009, 19:26
bigfernhead wrote:
A 400-meter runner spent 4 more seconds on the first half of the distance than he did on the second. If the runner finished the 400-meter distance in 50 seconds, what was his average speed for the first 200 meters?

a) 24 1/3 kmh
b) 25 1/3 kmh
c) 26 2/3 kmh
d) 27 2/3 kmh
e) 29 1/12 kmh


Its same. Either gives the same result.

1. x+x-4 = 50
x = 27
First half time = x = 27
Second half time = x - 4 = 27-4 = 23

Avg speed for the first half = 200m /x = 200m/27 = 200m/{27/(60*60)} per hour = (200m*60*60)/(27) = 200m*20*20/3 = 80km/3 = 26 2/3 per hour.

2. x+4+x = 50
x = 23
First half time = x +4 = 27
Second half time = x = 23

Avg speed for the first half = 200m /(x+4) = 200m/(23+4) = 200m/{27/(60*60)} per hour = (200m*60*60)/(27) = 200m*20*20/3 = 80km/3 = 26 2/3 per hour.
_________________

Verbal: http://gmatclub.com/forum/new-to-the-verbal-forum-please-read-this-first-77546.html
Math: http://gmatclub.com/forum/new-to-the-math-forum-please-read-this-first-77764.html
Gmat: http://gmatclub.com/forum/everything-you-need-to-prepare-for-the-gmat-revised-77983.html


GT

Kudos [?]: 841 [0], given: 19

Manager
Manager
avatar
Joined: 13 Jan 2009
Posts: 170

Kudos [?]: 26 [0], given: 9

Schools: Harvard Business School, Stanford
Re: Speed Question [#permalink]

Show Tags

New post 29 Apr 2009, 03:50
GMAT TIGER wrote:
bigfernhead wrote:
A 400-meter runner spent 4 more seconds on the first half of the distance than he did on the second. If the runner finished the 400-meter distance in 50 seconds, what was his average speed for the first 200 meters?

a) 24 1/3 kmh
b) 25 1/3 kmh
c) 26 2/3 kmh
d) 27 2/3 kmh
e) 29 1/12 kmh


Its same. Either gives the same result.

1. x+x-4 = 50
x = 27
First half time = x = 27
Second half time = x - 4 = 27-4 = 23

Avg speed for the first half = 200m /x = 200m/27 = 200m/{27/(60*60)} per hour = (200m*60*60)/(27) = 200m*20*20/3 = 80km/3 = 26 2/3 per hour.

2. x+4+x = 50
x = 23
First half time = x +4 = 27
Second half time = x = 23

Avg speed for the first half = 200m /(x+4) = 200m/(23+4) = 200m/{27/(60*60)} per hour = (200m*60*60)/(27) = 200m*20*20/3 = 80km/3 = 26 2/3 per hour.


Thanks GMAT TIGER! Good explanation.

Kudos [?]: 26 [0], given: 9

Manager
Manager
User avatar
Joined: 19 Aug 2006
Posts: 239

Kudos [?]: 13 [0], given: 0

Re: Speed Question [#permalink]

Show Tags

New post 29 Apr 2009, 06:55
GMAT TIGER wrote:
bigfernhead wrote:
A 400-meter runner spent 4 more seconds on the first half of the distance than he did on the second. If the runner finished the 400-meter distance in 50 seconds, what was his average speed for the first 200 meters?

a) 24 1/3 kmh
b) 25 1/3 kmh
c) 26 2/3 kmh
d) 27 2/3 kmh
e) 29 1/12 kmh


Its same. Either gives the same result.

1. x+x-4 = 50
x = 27
First half time = x = 27
Second half time = x - 4 = 27-4 = 23

Avg speed for the first half = 200m /x = 200m/27 = 200m/{27/(60*60)} per hour = (200m*60*60)/(27) = 200m*20*20/3 = 80km/3 = 26 2/3 per hour.

2. x+4+x = 50
x = 23
First half time = x +4 = 27
Second half time = x = 23

Avg speed for the first half = 200m /(x+4) = 200m/(23+4) = 200m/{27/(60*60)} per hour = (200m*60*60)/(27) = 200m*20*20/3 = 80km/3 = 26 2/3 per hour.


Thanks, made an error in the final calculation. This clears it.

Kudos [?]: 13 [0], given: 0

Re: Speed Question   [#permalink] 29 Apr 2009, 06:55
Display posts from previous: Sort by

Speed Question

  post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.