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# [#32] 2 Min. Challenge: Device

Author Message
CEO
Joined: 15 Aug 2003
Posts: 3454
[#32] 2 Min. Challenge: Device [#permalink]

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26 Mar 2004, 17:30
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

138

1. Time yourself
2. Solve as fast as you can

Mr. P, a mechanical engineer, has made three devices which he claims can reduce fuel consumption in cars by 25%, 30% and 45%, respectively. Mr. G buys these three devices and fits them into his car. The exact saving of fuel consumption will work out to (given that the three devices are independent in effect)

a. 100%
b. 71.125%
c. 65.25%
d. 75%
e. 80%
Director
Joined: 03 Jul 2003
Posts: 652

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26 Mar 2004, 17:44
My ans: b
Time = 3 mins
GMAT Club Legend
Joined: 15 Dec 2003
Posts: 4288

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26 Mar 2004, 19:28
B) between 2-3 min.
1 - .75*.7*.55 = .71125
_________________

Best Regards,

Paul

Senior Manager
Joined: 06 Dec 2003
Posts: 366
Location: India

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27 Mar 2004, 02:00
In accord with PAUL, Answer should be: 71.125% (B)

Dharmin
CEO
Joined: 15 Aug 2003
Posts: 3454
Re: [#32] 2 Min. Challenge: Device [#permalink]

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27 Mar 2004, 08:06
praetorian123 wrote:
138

1. Time yourself
2. Solve as fast as you can

Mr. P, a mechanical engineer, has made three devices which he claims can reduce fuel consumption in cars by 25%, 30% and 45%, respectively. Mr. G buys these three devices and fits them into his car. The exact saving of fuel consumption will work out to (given that the three devices are independent in effect)

a. 100%
b. 71.125%
c. 65.25%
d. 75%
e. 80%

Let us assume, before using the given three devices,
four-wheelers take X unit fuel.
By using all the three devices, fuel consumption will
reduced to

= X * (100тАУ25)* (100тАУ30)*(100тАУ45)
................................
100* 100 * 100
= 0.28875 X

Hence, percentage saving in fuel consumption

X - 0.28875X * 100 = 71.125%
................
X
Re: [#32] 2 Min. Challenge: Device   [#permalink] 27 Mar 2004, 08:06
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