Study these math problems and observe their solutions.

We have presented three math problems here..
These problems can be solved in more than one way.

Study these problems, observe their solutions.

We are sure you can replicate the solution process to other problems.
Version 1: questions 1 to 3



Visit  semanticslearning.com , click on GMAT tips for solutions

New feature in letsgmat

people have been asking me why the OG has 550 to 650 range of sums? I told them its makes business sense for OG to issue easy sums. So I have compiled list of higher order problems(750 to 800 range). I will weekly update them.

The problem+logic+solution is presented with each sum.
go ahead and lap it up

The logic has the thinking process behind the problem solving process..


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Math Problem solved using ScoT

I got a query from a in this problem. I solved using Science of Thinking(ScoT) approach.Observe the problem solving process.

The sum of the even numbers between 1 and n is 79*80, where n is an odd number, then n ?

These type of sums can be solved using my thinking skills – “pattern recognition” and “hypothesis testing”


Take sum of even numbers when n =5( N has to be an odd number)
Sum = 2+4 = 6 i.e 2 *3( Same pattern as 79*80 i.e n*(n-1))
Now take sum of even numbers when n = 7
Sum = 2+4+6 = 12 i.e 3*4

So you get a pattern 2*3, 3*4…………………….79*80
When n = 5,7……n
Do you observe that 2+3 =5 and 4+3 =7.

So our hypothesis is that n should be sum of the product of the numbers(in the form n*(n-1) which yields the sum of the even numbers.
Now lets check our hypothesis
When n =9
Sum = 2+4+6+8 = 20 = 4*5
4+5 is equal to n
Hence n can be concluded as 79+80=159

For more details visit http://www.semanticslearning.com/gmat-l3-method.asp
My math Ebook has all the thinking skills tested in GMAT.You can access the demo at
http://www.semanticslearning.com/gmat-home.asp Title GMAT higher order problem solving.

Cheers





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