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Source: — Problem Solving |
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by pemdas » Sat May 14, 2011 7:21 am
0.1001/(-1.002)^2 - 1 = 0.1001/{(-1.002 - 1}*(-1.002 + 1)} = 0.1001/{(-2.002)*(-0.002)} = 1001/{(-20020)*(-0.002)} = 1/{(-20)*(-0.002)}= 1000/(-20*(-2)) = 1000/40 = 25

ask yourself the following questions:
- do I know how to do this problem? Do I want to do the tedious calculations?
- what should I do when I don't know what to do? Is there an easier way to do this?
- are there any obvious traps?
- could I ballpark?



Strongt wrote:0.1001/(-1.002)^2 - 1

a. 0.025
b. 0.25
c. 2.5
d. 25
e. 250

OA is D

how to handle such questions?
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by pratul_mangal » Sat May 14, 2011 7:50 am
This question looks a bit scary due to third place decimal numbers, but it is very easy.

The -ve sigh in the denominator is just to distract mind, its of no use. So remove it and simply apply the formula: (a^2 -b^2) = (a + b)(a - b).

the number will become: 0.1001/(2.002 x 0.002)

on simplifying, it will give 1/0.004, which is 25.

Answer: (d)
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by Strongt » Sat May 14, 2011 8:21 am
Perfect :) really appreciate it guys
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