DI , PERCENTAGE and ratio...

from last few days i am getting reminder for posting some tricks on DI.... but DI has no trick.. why???? because tricks are used to get an exact answer of the question but in DI section most of the answer are approx...........

and this is the best part to solve DI..... we only have to find approx answer to any question .........    and for that i have ways..........

every DI is followed by set of 5 question... out of which 2 can solved by using ultimate trick..... rest 3 question have approx answer..........

NOTE- use ultimate trick only when addition and subtraction is asked because in these question answer are exact. never use the trick with ratio and percentage as they have approximate answer........

neither i am going to tell you any specific value of certain percentage like 12.5% = 1/8 and so on.... this you already knew nor i am going to tell u something new.......

believe me what i am going to tell , u already knew them but u dont knw how to apply it... thats the only problem......

lets take a number say 49486
Q. what is 50% of this no.? ( divide no. by 2)
Q. what is 25% of this no?  ( divide no. by4 or half of 50%)
Q. what is 10% of this no.? ( put decimal at ONES place)
Q. what is 5% of this no.?   ( half of 10% or put decimal to  
                                             ONES place for the answer of 50%)
Q. what is 1% of this no.?   ( put decimal at TENS place)
Q. what is 2% of this no.?    ( double of 1%)

all of u can tell the answer without using your pen and copy..... u can do this in your mind and can write the answer directly...... ryt na???????

now if we know these value , which we already knew , then any problem of DI be easily solved.......

mainly the question of DI deals with ratio and to some extent percentage..... ratio and percentage are interchangeable......
in DI we mainly get question like 
Q. X is how much % of y. = X/Y
Q. X increases y by how much %.=  X-Y/Y


so lets start with solving fraction as percentage.......

 Q. 660 is what percent of 5100?
   
solution = we know that 10% of 5100 is 510... ryt 
we need it to 660 .... ryt? and so far we have 510 therefore we only need 150 more to get the approx answer..........
 now if you look that 1% of 5100 is 51.... we need 150 more which means we need 1% 3times...
therefore our answer will be little less than 13 ( 10+3%) ....... the answer is 12.9%......

right now you will be feeling that it is much time that's  because you are not accustomed to this method and believe me after practicing 15 - 20 question you will be calculating the answer in your mind............

NOTE-- for solving such question your first step is very important...
               first look at 10% and  50% of the number ... it gives you a 
                rough idea of the answer
               you can make digit of numerator and denominator equal 
               by multiply or dividing by 10..... but always keep it in 
                 mind while giving you final answer....

Q. Dodo has Rs.230 initially but spend Rs.34 on 'mobile recharge'. what % of money is now left with him?

SOL-- 230-34/230
          = 196/230
now 10% of 230 is 23.... very small as compared to 196... leave it..
take 50% which is 115 somewhat closer but still the difference is 80...
now half of 115 (25%)= 57(approx).... and 10% = 23
 now total is 50%+25%+10%= 85 approx .......... 
and 115+57+23 = 195
see u get the answer.....

you may feel problem in calculating the way i am doing ... so now i will tell you how i started doing it.....

 Q. 256/290

below is the way i used to calculate in starting......

Percentage	Amount 256 /290
50%	145
25%	72 (39 more needed for 256)
12.5+1% total= 88.5	36 + 1%= 38.9 255.9

NOTE- after taking 2nd%(25% in this case) locate the remaining difference always........ 

so ur answer will be 88.5 approx......
with practice you can simply write % value and total it to get the answer........

LETS TAKE ONE MORE EXAMPLE...

Q.7526 is what % of 67....

 our fraction is 7526/6700 ( making equal)
now as our numerator is greater therefore ans will be more than 100...... ryt na????
difference between them is nearly 826...

Percentage	Amount 826 for 6700
10%	670
2%	67 *2= 134
(initial)100+10+2=112	804

  so our answer sud be approx. 112.xx..........................

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