NEW HERE? LEARN MORE
closeclose
Last visit was: 24 Apr 2024, 09:12 It is currently 24 Apr 2024, 09:12
Decision Tracker
My Rewards
New posts
New comers' posts

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

In a 1 km race, A gives B a start of 20 seconds and beats him by 40m.

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92902
Own Kudos [?]: 618765 [4]
Given Kudos: 81587
Send PM
CAT Tests Forum Quiz Mode
In a 1 km race, A gives B a start of 20 seconds and beats him by 40m. [#permalink] New post   30 Nov 2021, 01:47
4
Bookmarks
Expert Reply
00:00
A
B
C
D
E

Difficulty:

85% (hard)

Question Stats:

50% (02:29) correct 50% (02:18) wrong based on 68 sessions
Hide Show timer Statistics
In a 1 km race, A gives B a start of 20 seconds and beats him by 40m. However, when he gives B a start of 25 seconds they finish in a dead heat. What is A’s speed in m/sec?

(A) 2 m/sec
(B) 8 m/sec
(C) 10 m/sec
(D) 12.5 m/sec
(E) 20 m/sec
ShowHide Answer
Official Answer
C
User avatar
L
Kinshook
GMAT Club Legend
GMAT Club Legend
Joined: 03 Jun 2019
Posts: 5343
Own Kudos [?]: 3964 [1]
Given Kudos: 160
Location: India
Schools: HBS '22 CBS '22 Wharton '22
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Send PM
Reviews Badge
In a 1 km race, A gives B a start of 20 seconds and beats him by 40m. [#permalink] New post   26 Dec 2021, 10:13
1
Kudos
Given: In a 1 km race, A gives B a start of 20 seconds and beats him by 40m. However, when he gives B a start of 25 seconds they finish in a dead heat.
Asked: What is A’s speed in m/sec?

Let A's speed be x m/s and B's speed be y m/s

In a 1 km race, A gives B a start of 20 seconds and beats him by 40m.
Distance travelled by B in 20 seconds = 20y
Time taken by A to complete 1 km race = 1000/x seconds
B travels total distance of 1000 - 40 = 960 m
20y + (1000/x)*y = 960. (1)

When he gives B a start of 25 seconds they finish in a dead heat.
Distance travelled by B in 25 seconds = 25y
Time taken by A to complete 1 km race = 1000/x seconds
25y + (1000/x)*y = 1000. (2)

(2) - (1)
5y = 40
y = 40/5 = 8 m/s

25y + (1000/x)*y = 1000
200 + 8000/x = 1000
8000/x = 800
x = 10 m/s

IMO C
avatar
B
ankurgarg2410
Intern
Intern
Joined: 19 Dec 2021
Posts: 7
Own Kudos [?]: 18 [4]
Given Kudos: 0
GRE 1: Q170 V152
Send PM
Re: In a 1 km race, A gives B a start of 20 seconds and beats him by 40m. [#permalink] New post   27 Dec 2021, 08:11
3
Kudos
1
Bookmarks
In a 1 km race, A gives B a start of 20 seconds and beats him by 40m. However, when he gives B a start of 25 seconds they finish in a dead heat. What is A’s speed in m/sec?
(A) 2 m/sec
(B) 8 m/sec
(C) 10 m/sec
(D) 12.5 m/sec
(E) 20 m/sec

Solution:
When B gets a head start of 20 sec, he falls short by 40m. However, when he gets the head start of 25 sec, he finished right alongside A. This implies, that B can run 40m in 5 sec. Hence speed of B is 8m/s.
when he gives B a start of 25 seconds - B got the head start of 200m. Hence, B runs for 800m in the time A runs 1000m. Ratio of speeds = 8:10. Hence, speed of A = 10m/s.
User avatar
B
hardikkjagga
Intern
Intern
Joined: 22 Aug 2023
Posts: 1
Own Kudos [?]: 0 [0]
Given Kudos: 20
Send PM
Re: In a 1 km race, A gives B a start of 20 seconds and beats him by 40m. [#permalink] New post   27 Dec 2023, 01:20
in the extra 5 seconds that a gives b , b runs 40m ,
so b's speed = 40/5 i.e. 8 m/s
b will take 1000/8 = 125 seconds to complete race
so a will take 125-25= 100 seconds to complete 1000m race
so a's speed = 1000/100 = 10m/s
GMAT Club Bot
gmatclubot
Re: In a 1 km race, A gives B a start of 20 seconds and beats him by 40m. [#permalink]
27 Dec 2023, 01:20
Moderators:
Bunuel
Math Expert
92902 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions