Join us for MBA Spotlight – The Top 20 MBA Fair      Schedule of Events | Register

 It is currently 06 Jun 2020, 19:57

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

In a 10 km race. A, B, and C, each running at uniform speed, get the

Author Message
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 64322
In a 10 km race. A, B, and C, each running at uniform speed, get the  [#permalink]

Show Tags

02 Apr 2020, 10:29
00:00

Difficulty:

55% (hard)

Question Stats:

61% (02:12) correct 39% (01:25) wrong based on 41 sessions

HideShow timer Statistics

In a 10 km race. A, B, and C, each running at uniform speed, get the gold, silver, and bronze medals, respectively. If A beats B by 1 km and B beats C by 1 km, then by how many metres does A beat C?

A. 1750
B. 1800
C. 1900
D. 1950
E. 2000

_________________
Director
Joined: 16 Jan 2019
Posts: 616
Location: India
Concentration: General Management
WE: Sales (Other)
Re: In a 10 km race. A, B, and C, each running at uniform speed, get the  [#permalink]

Show Tags

02 Apr 2020, 10:40
1
2
The distance between B and C increases at the rate 1km for every 10km

So when B runs 9km, the distance between B and C must be 9/10=0.9km=900m

Distance AC = AB+BC = 1000+900 = 1900m

Posted from my mobile device
Intern
Joined: 08 Jul 2019
Posts: 32
Location: United Kingdom
Concentration: Strategy, General Management
GMAT 1: 620 Q46 V38
GPA: 3.51
WE: General Management (Computer Software)
Re: In a 10 km race. A, B, and C, each running at uniform speed, get the  [#permalink]

Show Tags

02 Apr 2020, 10:57
1
when a reaches finish line b reaches 9km (i)
when b reaches finish line c reaches 9km (ii)

from (i) same equating time

S denotes speed

10/S(a)=9/S(b)

=> 10/9S(a) =1/S(b)

similarly from ii

10/s(b) = 9/s(c)

1/s(b)= 9/10s(c)

equating for 1/s(b), we get relation between s(a) and s(c)

10/9S(a) =9/10s(c) => s(c)=81S(a)/100

running at uniform speed c could only cover 81/100 of distance covered by A

so while covering 10000 metres c could only cover 81/100*10000=8100

DS Forum Moderator
Joined: 19 Oct 2018
Posts: 1890
Location: India
Re: In a 10 km race. A, B, and C, each running at uniform speed, get the  [#permalink]

Show Tags

02 Apr 2020, 11:27
3
1
Speed of A, B, and C are $$S_A$$, $$S_B$$ and $$S_C$$ respectively.

$$S_A : S_B = 10:9$$

$$S_B : S_C = 10:9$$

$$S_A : S_B : S_C = 10*10 : 9*10 : 9*9 = 100 : 90 : 81$$

A beat C by 1.9 (10-8.1) Km or 1900m.

Bunuel wrote:
In a 10 km race. A, B, and C, each running at uniform speed, get the gold, silver, and bronze medals, respectively. If A beats B by 1 km and B beats C by 1 km, then by how many metres does A beat C?

A. 1750
B. 1800
C. 1900
D. 1950
E. 2000
Intern
Joined: 15 Jan 2019
Posts: 21
Re: In a 10 km race. A, B, and C, each running at uniform speed, get the  [#permalink]

Show Tags

02 Apr 2020, 12:23
1
nick1816 wrote:
Speed of A, B, and C are $$S_A$$, $$S_B$$ and $$S_C$$ respectively.

$$S_A : S_B = 10:9$$

$$S_B : S_C = 10:9$$

$$S_A : S_B : S_C = 10*10 : 9*10 : 9*9 = 100 : 90 : 81$$

A beat C by 1.9 (10-8.1) Km or 1900m.

Bunuel wrote:
In a 10 km race. A, B, and C, each running at uniform speed, get the gold, silver, and bronze medals, respectively. If A beats B by 1 km and B beats C by 1 km, then by how many metres does A beat C?

A. 1750
B. 1800
C. 1900
D. 1950
E. 2000

An excellent way to solve it!!!!
Took me close to 4 min by the traditional (R*T=D) method
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 10683
Location: United States (CA)
Re: In a 10 km race. A, B, and C, each running at uniform speed, get the  [#permalink]

Show Tags

04 Apr 2020, 13:40
Bunuel wrote:
In a 10 km race. A, B, and C, each running at uniform speed, get the gold, silver, and bronze medals, respectively. If A beats B by 1 km and B beats C by 1 km, then by how many metres does A beat C?

A. 1750
B. 1800
C. 1900
D. 1950
E. 2000

Let’s let the time A runs the 10 km (or 10,000-meter) race be 1000 seconds. Thus, A’s speed is 10,000/1000 = 10 m/s. Since B is 1 km behind A when A finishes the race, B runs 9 km, or 9000 meters, in 1000 seconds. Thus, B’s speed is 9000/1000 = 9 m/s. In other words, B runs the 10 km race in 10,000/9 seconds. Since C is 1 km behind B when B finishes the race, C runs 9 km, or 9000 meters, in 10,000/9 seconds. So C’s speed is 9000/(10,000/9) = 9/(10/9) = 81/10 = 8.1 m/s.

Now, let’s compare A and C when A finishes the race. A finishes the 10 km race in 1000 seconds (see above). During this time, C runs 8.1 x 1000 = 8100 meters. Therefore, A beats C by 10,000 - 8100 = 1900 meters.

_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
202 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.

Re: In a 10 km race. A, B, and C, each running at uniform speed, get the   [#permalink] 04 Apr 2020, 13:40