1000 DS section 5 #24

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1000 DS section 5 #24

by rookiez » Thu Jul 09, 2009 12:29 am
24. All trainees in a certain aviator training program must take both a written test and a flight test. If 70 percent of the trainees passed the written test, and 80 percent of the trainees passed the flight test, what percent of the trainees passed both tests?
(1) 10 percent of the trainees did not pass either test.
(2) 20 percent of the trainees passed only the flight test.

OA D
Source: — Data Sufficiency |

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by mike22629 » Thu Jul 09, 2009 3:39 am
For these problems use matrix (best way to do these problems in my opinion)

Lets see if i can set up so it shows up well on post:
We know that 70% passed written test and 80% passed flight
(bold will be given information)

---------------Passed Written Test----------Failed Written test----total
Passed Flight-------x-------------------------------y-----------------80%

Failed Flight---------z------------------------------w-----------------20%

Total----------------70%--------------------------30%--------------100%

A) w = 10%
So as you can see, if w = 10% y = 20% (y+w = 30%)
Then since x + y = 80%, x = 60%

B) y = 20%, so same as in A, x + y = 80%, so x = 60%

OA D.

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by mike22629 » Thu Jul 09, 2009 3:39 am
oops forgot to bold given info, but I still think its pretty clear.

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by shibal » Thu Jul 09, 2009 2:05 pm
x=a+b-both+neither

i.e. 100=70+80-both+10.....

with both stmts we can find out both.... hence d