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

Redeem

MGMAT TIME SPEED DIST

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 26
Joined: Wed Apr 30, 2008 11:05 am
Location: India

MGMAT TIME SPEED DIST

by anksbhandari » Sat Aug 02, 2008 9:28 am
Tom and Linda stand at point A. Linda begins to walk in a straight line away from Tom at a constant rate of 2 miles per hour. One hour later, Tom begins to jog in a straight line in the exact opposite direction at a constant rate of 6 miles per hour. If both Tom and Linda travel indefinitely, what is the positive difference, in minutes, between the amount of time it takes Tom to cover half of the distance that Linda has covered and the amount of time it takes Tom to cover twice the distance that Linda has covered?

a. 60
b. 72
c. 84
d. 90
e. 108
Top
Source: — Problem Solving |
Legendary Member
Posts: 661
Joined: Tue Jul 08, 2008 12:58 pm
Location: France
Thanked: 48 times

by pepeprepa » Sat Aug 02, 2008 10:09 am
Would say E
Top
Senior | Next Rank: 100 Posts
Posts: 88
Joined: Tue Jul 15, 2008 1:43 am
Thanked: 3 times
Followed by:1 members
GMAT Score:590

by eccentric » Sat Aug 02, 2008 11:31 am
Distance covered by Linda in a min = 1/30
Distance covered by Tom in a min = 1/10

In 120 mins tom would be exactly 2 times the distance covered by Linda.
while he starts an hour later by that time Linda would have covered 2miles now it takes 12 minutes for Tom to reach 1.2 miles which is exactly 1/2 the distance covered by linda in the same time.
hence 120-12 = 108 is correct choice...
Top
Master | Next Rank: 500 Posts
Posts: 178
Joined: Wed May 14, 2008 3:51 pm
Thanked: 16 times
Followed by:1 members
GMAT Score:99%+

Re: MGMAT TIME SPEED DIST

by egybs » Sat Aug 02, 2008 11:32 am
We know Linda has already traveled 2 miles before things really get going:

(2+2t)(1/2) = 6t
1+t = 6t
t =1/5 = 12 min

(2+2t)(2) = 6t
4+4t = 6t
2t = 4
t =2 or 120 minutes

120 min - 12 min = 108 min.

E

anksbhandari wrote:Tom and Linda stand at point A. Linda begins to walk in a straight line away from Tom at a constant rate of 2 miles per hour. One hour later, Tom begins to jog in a straight line in the exact opposite direction at a constant rate of 6 miles per hour. If both Tom and Linda travel indefinitely, what is the positive difference, in minutes, between the amount of time it takes Tom to cover half of the distance that Linda has covered and the amount of time it takes Tom to cover twice the distance that Linda has covered?

a. 60
b. 72
c. 84
d. 90
e. 108
Top
Legendary Member
Posts: 829
Joined: Mon Jul 07, 2008 10:09 pm
Location: INDIA
Thanked: 84 times
Followed by:3 members

by sudhir3127 » Sat Aug 02, 2008 9:24 pm
Hi understood the 120 minutes .. but can someone explain me the 12 mints ?
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 200
Joined: Sun Jun 17, 2007 10:46 am
Location: Canada
Thanked: 9 times

Re: MGMAT TIME SPEED DIST

by beeparoo » Mon Aug 04, 2008 10:02 am
egybs wrote:We know Linda has already traveled 2 miles before things really get going:

(2+2t)(1/2) = 6t
1+t = 6t
t =1/5 = 12 min

(2+2t)(2) = 6t
4+4t = 6t
2t = 4
t =2 or 120 minutes

120 min - 12 min = 108 min.

E

anksbhandari wrote:Tom and Linda stand at point A. Linda begins to walk in a straight line away from Tom at a constant rate of 2 miles per hour. One hour later, Tom begins to jog in a straight line in the exact opposite direction at a constant rate of 6 miles per hour. If both Tom and Linda travel indefinitely, what is the positive difference, in minutes, between the amount of time it takes Tom to cover half of the distance that Linda has covered and the amount of time it takes Tom to cover twice the distance that Linda has covered?

a. 60
b. 72
c. 84
d. 90
e. 108
@ sudhir3127: If you understood the set up of equations that egybs used, especially for that which resulted in 120 minutes, how do you have trouble understanding the set up which resulted in 12 minutes?
They are the same logic.

(2+2t)(1/2) = 6t <---Here (1/2)Distance of Linda = Distance of Tom
1+t = 6t
t =1/5 = 12 min <--- Here, Time(of Tom) = 1/5 hr*(60 min/hr) = 12 min
GMAT obsession begone - girl needs her social life back.
Top
Post new topic Post Reply
• Page 1 of 1