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Source: — Data Sufficiency |
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by tohellandback » Thu Jun 18, 2009 12:51 am
IMO E
plugin numbers
let x=60 miles
speed is 60 miles per hour
55 miles in 55 minutes
5 miles in 10 minutes
total time=65 minutes
total time he should have taken=60 minute
(5/60)*100=50/6

E=500/x=500/60=50/6
The powers of two are bloody impolite!!
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by bluementor » Thu Jun 18, 2009 3:31 am
we have two scenarios here:

1) Don travels for 5 miles at 30mph, and x-5 miles at 60mph. Total time travelled = t1
2) Don travels for x miles at an average of 60 mph. Total time travelled = t2

((t1 - t2)/t2 )*100 ?

Scenario 1:

t1 = 5/30 + (x-5)/60
t1 = 10/60 + (x-5)/60
t1 = (x + 5)/60

Scenario 2:

t2 = x/60

Therefore,

((t1 - t2)/t2 )* 100 = ((x + 5)/60 - x/60)/(x/60)*100 = 500/x

Choose E.

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