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

Redeem

Manhatta advanced Quant

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 116
Joined: Wed Oct 03, 2012 10:44 pm
Thanked: 5 times
Followed by:1 members

Manhatta advanced Quant

by theachiever » Thu Dec 20, 2012 11:15 pm
Truck A is on a straight highway heading due south at the same time Truck B is on a different straight highway heading due east. At 1:00PM, Truck A is exactly 14 miles north of Truck B.If both trucks are travelling at a constant speed of 30 miles per hour,at which of the following times will they be exactly 10 miles apart?
  • A.1:10PM
    B.1:12PM
    C.1:14PM
    D.1:15PM
    E.1:20PM
Resilience is a trait that manifests in an individual when he/she faces consistent failures motivating them to succeed in the end.
Top
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 131
Joined: Wed Nov 14, 2012 2:01 pm
Thanked: 39 times
Followed by:2 members

by puneetkhurana2000 » Thu Dec 20, 2012 11:45 pm
Answer is B.

After 1:00 PM, truck B will be moving away from Truck A and towards east, so they will form a right angle triangle with sides 6, 8, 10. (As we have to find the time when they are 10 miles apart).

Both have same speed, so cover same amount of distance in same time.

They will cover 6 miles in 12 minutes. (30/60 * 12).

So the Right angle triangle will be like
6..horizontal distance covered by B
8..vertical distance to be covered by A (14 -6)
10 ...the distance between them.

Answer is B.
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 194
Joined: Mon Oct 15, 2012 7:14 pm
Location: India
Thanked: 47 times
Followed by:6 members

by The Iceman » Fri Dec 21, 2012 12:45 am
By symmetry there will be two instants when they will be exactly 10 miles apart. Both will be the case when 6-8-10 right angled triangle will be formed.

The first when each travels 6 miles and the second when each travels 8 kms.

Hence two possible instants are 1:00 + 6*60/30 and 1:00 + 8*60/30 or 1:12 PM and 1:16 PM.

Of the two the former is present in the options. Hence option B is the right choice :)

PS: The problem would have been funnier (read trickier) if it had been a DS problem as there are two possibilities and the info is not sufficient to uniquely determine one instant of time.
Top
Post new topic Post Reply
• Page 1 of 1