Target Test Prep 20% Off Flash Sale is on! Code: FLASH20

Redeem
Target Test Prep Flash Sale
Target Test Prep is 20% off right now!
Use code FLASH20

Available with Beat the GMAT members only code

MORE DETAILS
Magoosh
Magoosh
Study with Magoosh GMAT prep

Available with Beat the GMAT members only code

MORE DETAILS
Magoosh

plane flies along

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
GMAT Instructor
Posts: 3650
Joined: Wed Jan 21, 2009 4:27 am
Location: India
Thanked: 267 times
Followed by:80 members
GMAT Score:760

plane flies along

by sanju09 » Fri Mar 05, 2010 6:29 am
A plane flies along the four sides of a square ground at speeds of 100, 200, 300, and 400. What is plane's average speed in the whole trip?
(A) 250
(B) 192
(C) 150
(D) 124
(E) 108
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com
Top
Senior | Next Rank: 100 Posts
Posts: 45
Joined: Tue Mar 02, 2010 4:27 am
Thanked: 2 times

by yeahdisk » Fri Mar 05, 2010 6:43 am
for a square of side 1

Time taken = [spoiler]1/100 + 1/200 + 1/300 + 1/400 = 25/1200[/spoiler]

Distance = 4

Average speed = [spoiler]4 / (25/1200) = 4800/25 = 192[/spoiler]
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 142
Joined: Sat Feb 20, 2010 7:23 pm
Thanked: 8 times
Followed by:1 members

by bpgen » Fri Mar 05, 2010 7:51 am
Absolutely right, we should not just do the Arithmetic(mean) of all those speeds.
We need to find out time spent during each different speeds and then divide total distance by total time.
"Ambition is the path to success. Persistence is the vehicle you arrive in."
Top
Post new topic Post Reply
• Page 1 of 1