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Choosing between any of the groups in the attached image, and the rest of the numbers are the non-friends one must choose from
The probability:
=((2C1 X 5C1) + (2C1 x C1) + (3C1 x 4C1))/(7C1 x 6C1)
=32/42
=16/21
Hence (E)
Wish I could explain more clearly, nice question though.
Regards
- by chitoshia
Mon May 14, 2007 4:59 am- Forum: Problem Solving
- Topic: MGMAT - probability
- Replies: 3
- Views: 1764
- by chitoshia
Thu May 10, 2007 4:16 am- Forum: Problem Solving
- Topic: GMATPrep - exponents again
- Replies: 4
- Views: 1857
A clumsy way of doing it (backsolving) A----------------B R --- W --- R --- W 1 --- 3 --- 17/4 --- 17 3 --- 9 --- 21/4 --- 21 4 --- 12 --- 18/4 --- 18 6 --- 18 --- 3 --- 12 8 --- 24 --- 6/4 --- 6 Hence 6 implies D. Regards Sorry, but the editing is lost in the posting. Take first option, 1 red marbe...
- by chitoshia
Tue May 08, 2007 11:46 pm- Forum: Problem Solving
- Topic: Ratio Problem
- Replies: 5
- Views: 2094
It is 0.
13^7+16^7+15^7+14^7
=(13+16) (smth) + (15+14) (smth)
= (29) (smth)
which leaves
(smth)/2
smth is even, thus 0
why is smth even?, the numerator in the problem is even (sum of three odds), and odd multiple out will leave it even.
regards
- by chitoshia
Tue May 08, 2007 6:37 am- Forum: Problem Solving
- Topic: need an explanation
- Replies: 4
- Views: 1693
Hi, My answer doesnt match the options, but i find it logical enough to be correct (hopefully!) for 120 feet, he moves at 6 f/s and for the remaining distance he moves at 3 f/s. time in each section, 120/6 = 20 s and 180/3 = 60 s total distance/total time = 300/80 = 3.75 f/s please comment. otherwis...
- by chitoshia
Tue May 08, 2007 6:06 am- Forum: Problem Solving
- Topic: Conveyor belt and average speed
- Replies: 5
- Views: 6420