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metallicafan
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Joined: 04 Oct 2009
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Status:2000 posts! I don't know whether I should feel great or sad about it! LOL
Location: Peru
Concentration: Finance, SMEs, Developing countries, Public sector and non profit organizations
Schools:Harvard, Stanford, Wharton, MIT & HKS (Government)
GPA: 4.0
WE 1: Economic research
WE 2: Banking
WE 3: Government: Foreign Trade and SMEs
02 Mar 2012, 09:28
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E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
5%
(low)
Question Stats:
90% (01:31) correct
10%
(02:16)
wrong
based on 194
sessions
History
Date
Time
Result
Not Attempted Yet
Airplanes A and B traveled the same 360-mile route. If airplane A took 2 hours and airplane B traveled at an average speed that was \(\frac{1}{3}\) slower than the average speed of airplane A, how many hours did it take airplane B to travel the route?
(A) 2
(B) \(2\frac{1}{3}\)
(C) \(2\frac{1}{2}\)
(D) \(2\frac{2}{3}\)
(E) 3
I agree with the OA.
However, something that I don't understand is why cannot analyze it in this way:
The question says that airplane B traveled at an average speed that was \(\frac{1}{3}\) slower than the average speed of airplane A, right?
The OE says that, based on this info, that airplane A travels at 180 mph, so airplane B travels at 120 mph (1/3 slower).
Why cannot "1/3 slower" mean this?
A ---- 180 miles / 1 hour
B ---- 180 miles /[(4/3)*1hour]
The answer would be different.
Please, your comments.
Source: https://www.gmathacks.com
(A) 2
(B) \(2\frac{1}{3}\)
(C) \(2\frac{1}{2}\)
(D) \(2\frac{2}{3}\)
(E) 3
I agree with the OA.
However, something that I don't understand is why cannot analyze it in this way:
The question says that airplane B traveled at an average speed that was \(\frac{1}{3}\) slower than the average speed of airplane A, right?
The OE says that, based on this info, that airplane A travels at 180 mph, so airplane B travels at 120 mph (1/3 slower).
Why cannot "1/3 slower" mean this?
A ---- 180 miles / 1 hour
B ---- 180 miles /[(4/3)*1hour]
The answer would be different.
Please, your comments.
Source: https://www.gmathacks.com
02 Mar 2012, 09:47
Kudos
Bookmarks
metallicafan
The red part should be 3/2.
I'd approach this question in different manner and hope that it helps you to understand the question better.
Since B traveled at an average speed that was \(\frac{1}{3}\) slower than the average speed of airplane A, then the speed of B was \(\frac{2}{3}\) of that of A (\(x-\frac{1}{3}x=\frac{2}{3}x\)). So, airplane B would need \(\frac{3}{2}\) times more time to cover the same distance: \(2*\frac{3}{2}=3\) hours. That's because time*rate=distance, so if you decrease rate 2/3 times you'll need 3/2 times as many hours to cover the same distance.
Answer: E.
jlgdr
Joined: 06 Sep 2013
Last visit: 24 Jul 2015
Posts: 1,299
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Concentration: Finance
Schools: Wharton '17 (A) HBS '17 (WA$)
31 Dec 2013, 10:41
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metallicafan
Easy question
A traveled at 180mph
2/3*180 = 120mph
Hence B made the trip in 360/120 = 3 hours
Or recall that as distance is constant, then B will need 3/2 as much time as A to cover same distance
So it will give 3 as well
Hope it helps
Cheers!
J
