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If 1/2 of the air in a tank is removed with each stroke of a
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Updated on: 13 May 2014, 05:32
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Question Stats:
64% (01:13) correct 36% (01:10) wrong based on 592 sessions
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If 1/2 of the air in a tank is removed with each stroke of a vacuum pump, what fraction of the original amount of air has been removed after 4 strokes ?
Could someone please help me out with the below problem:
If 1/2 of the air in a tank is removed with each stroke of a vacuum pump, what fraction of the original amount of air has been removed after 4 strokes?
A. 15/16 B. 7/8 C. 1/4 D. 1/8 E. 1/16
This question is actually from the OG 12th edition. Am not able to understand the explanation given in OG for this problem. Could someone please explain in detail as to how to solve this
The best thing to do here is plug in Assume that there is 16 units of air in the tank first stroke = 1/2*16 = 8 ( we are left ith 8 now) second stroke = 1/2*8 = 4( left ith 4 units now) third stoke = 1/2*4 = 2( left with 2 units) 4th stroke = 1/2* 2 = 1 (left with 1 unit)
total units removed = 8+4+2+1 = 15 total unis in the tank at the begining = 16 thus its A . 15/16
so first stroke = 1/2 second stroke = 1/4 third stroke = 1/8 fourth stroke = 1/16
8/16 + 4/16 + 2/16 + 1/16 = 15/16
puma wrote:
if 1/2 of the air in a tank is removed with each stroke of a vacuum pump, what fraction of the original amount of the air has been removed after 4 strokes?
A) 15/16 B) 7/8 C) 1/4 D) 1/8 E) 1/16
_________________
------------------------------------ J Allen Morris **I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$.
if 1/2 of the air in a tank is removed with each stroke of a vacuum pump, what fraction of the original amount of the air has been removed after 4 strokes?
Oh, I get it..! Thanks..!!! I think the catch over here is.."the tank is halved after each stroke"....failed to understand the question properly. Thought that a single stoke halves the air in it...so after 2 strokes guessed there wont be any air in it
Let P is 100 ( 1 - 50/100)^4 Remaining amount = 100(1/16)
if 1/16 of 100 is remaining means 1-1/16 = 15/16 is lost.
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Piyush K ----------------------- Our greatest weakness lies in giving up. The most certain way to succeed is to try just one more time. ― Thomas A. Edison Don't forget to press--> Kudos My Articles: 1. WOULD: when to use?| 2. All GMATPrep RCs (New) Tip: Before exam a week earlier don't forget to exhaust all gmatprep problems specially for "sentence correction".
Re: If 1/2 of the air in a tank is removed with each stroke of a
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13 May 2014, 05:32
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puma wrote:
If 1/2 of the air in a tank is removed with each stroke of a vacuum pump, what fraction of the original amount of air has been removed after 4 strokes ?
If 1/2 of the air in a tank is removed with each stroke of a
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23 Jan 2017, 15:50
puma wrote:
If 1/2 of the air in a tank is removed with each stroke of a vacuum pump, what fraction of the original amount of air has been removed after 4 strokes ?
A. 15/16 B. 7/8 C. 1/4 D. 1/8 E. 1/16
let's assign a nice number..16 (divisible by 2 and 4), for total Air.. after 1st stroke, we are left with 8 after 2nd stroke, we are left with 4 after 3rd stroke, we are left with 2 after 4th stroke, we are left with 1
Re: If 1/2 of the air in a tank is removed with each stroke of a
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19 Mar 2018, 10:11
Hi All,
TESTing Values will work well on this question. A quick look at the answers tells us that the common denominator for all 5 options is 16; THAT is a huge clue that 16 would be a great number to TEST.
We're told that 1/2 of the air in a tank is removed with each stroke. We're asked what fraction has been removed after 4 strokes….
Full = 16 1st = 16-8 = 8 left 2nd = 8-4 = 4 left 3rd = 4-2 = 2 left 4th = 2-1 = 1 left
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64% (01:13) correct 
