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GeekInterview.com > Placement Papers > Infosys > Analytical
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Question: A and B write a test
A says " i got a third of the ques. wrong"
B says " i got 5 wrong"
together they got three quarters of the questions correct.
how many did a get correct.
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| November 11, 2006 11:52:09 |
#3 |
| Nitin |
Member Since: Visitor Total Comments: N/A |
RE: A and B write a testA says " i got a third o...
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| Hey where did you get 3/4 * 2x from. what rule did you apply. I too have solution:(here 'v' => union & '^' => intersection)|A| = x/3|B| = 5|A v B| = 3x/4so,| A' | = 2x/3| B' | = x - 5we know that,|A v B| = |A| + |B| - |A ^ B|applying this we get,| A ^ B | = 5x/12 - 5and| A' | + | B' | = | A' v B' | + | A' ^ B' |also applying de Morgan's law (see: http://mathworld.wolfram.com/deMorgansLaws.html)| A' | + | B' | = | (A ^ B)' | + | (A v B)' |that is2x/3 + (x-5) = [ x - (5x/12 -5)] + (x - 3x/4)=> 5x/3 -5 = 7x/12 + 5 + x/4=> 10x/12 = 10=> x = 12there for A got 2x/3 correct which is 8 questions correct. |
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