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Mensa Math/Logic Problems...How to Solve?

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#1 marcussoori

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Posted 07 September 2013 - 06:46 PM

I am unable to find similar problems or solutions online, so I thought I'd ask here...I'd really appreciate it if you all could help me learn how to solve these types of problems, so please include the correct reasoning process and solution, if you don't mind.

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#2 Anza Power

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Posted 07 September 2013 - 08:17 PM

So many, don't have the energy to go through them all...

The "find the missing number" type of questions don't usually have a strategy, you just stare at them and try to draw connections, look for patterns like for example are the numbers rising or falling, usually the answer should be very simple like taking a number and summing it's two digits and stuff like that.

Spoiler for 5/20

Spoiler for 10/20

Spoiler for 11/20

Spoiler for 12/20

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#3 Anza Power

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Posted 07 September 2013 - 08:28 PM

Spoiler for 5/20

Spoiler for 9/20

Spoiler for 14/20

Spoiler for /20

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#4 flamebirde

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Posted 07 September 2013 - 10:39 PM

Spoiler for 13/20

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Mafiosos and mafiosas of the world, unite! And then kill each other in a particularly tricky move that everyone suspects but never anticipates.

stand back. I'm going to apply logic.

Come join the battle against the Chromatic Witch! http://brainden.com/...nly-eat-orange/

The Coup of Rhotus still needs players!End the 2 year sign up phase! http://brainden.com/...-mafia-signups/

#5 marcussoori

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Posted 07 September 2013 - 11:34 PM

Thanks for all the answers, esp. 11/20!  I forgot that equation from high school math.

I have an alternate solution for 9/20, the shapes problem.

6               3           5            4            4

\               \         /   \           /             /

\              \      /      \         /             /

\             \   /         \       /             /

\            \/            \     /             /

\          /\             \   /             /

\      /   \             / \             /

\   /     \           /  \           /

-1       \     +1        -1            ?  ----> +1    (so 4+1 = 5)

So are there multiple solutions to these problems?

Edited by marcussoori, 07 September 2013 - 11:34 PM.

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#6 marcussoori

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Posted 07 September 2013 - 11:38 PM

For the second 9/20, answer is 62?  Multiply 2 numbers outside of circle, subtract the multiplication of the two remaining numbers, and you have the number in the middle of the circle.

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#7 marcussoori

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Posted 07 September 2013 - 11:41 PM

For the first image, 4/20, answer is 75.  For each row, add the two numbers, and then reverse the digits.  If the addition results in a number over 100, add the 1 to the last digit, then reverse the resulting two digit number.

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#8 marcussoori

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Posted 07 September 2013 - 11:49 PM

For the third image, 8/20, isn't there an error on the last row of the problem?  I am using the XOR method you described (add images and remove overlapping areas).  Anyway, I believe the solution is the fifth option.

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#9 marcussoori

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Posted 07 September 2013 - 11:56 PM

I still can't figure out 15/20...anyone?

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#10 marcussoori

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Posted 08 September 2013 - 12:04 AM

I also can't solve the 2nd 4/20

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