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Solution to version 1 questions (Updated On Tuesday, October 15, 2013)

Version 1 Question 2
A,B,C work together and complete a work . If they work together ,they take  
2 days less than the number of days A would have taken to do alone.
10 days less than the number of days B would have taken to do   alone 
1/3rd  the number of days that C would have taken if he works alone. 
How long did it take them to do all the work? 
1.3 2.2 3.5 4.6            5.7

First method: 
 Let us assume that all of them complete the job in 'd' days 
The number of days they take is A=>d+2 days,B=>d+10days   C=>3d days 
Work done per day by each of them is A= 1/(d+2) ,B  = 1/(d+10) ,C =1/3d. 
Work completed by all of them  working together in 1 day (1/d+2)+(1/d+10)+(1/3d)=1/d
d =3

Second Method:
Working with answer options 
  Let us take it the first option =>3 days Then. A will take 5 days 
If A,B and C complete 100% of  the work in 3 days, A does the work in 5days . 
i.e. A does 3/5 of the work =3/5100=60%  
Similarly B takes 13 days to complete the work
i.e  B does 3/13th of the work =>3/13100=23.3% 
C  takes 9 days i.e  C does 3/9th of the work= 3/9100=33.3% .
60%+23.3%+33.3%  doesn't add to 100%. 
so this is not correct answer. 

Take option 2, 
Total days is 2 
then A takes 4 days=>2/4100=50% 
B takes 12 days=>2/12100=16.66% 
C takes 6 days=>1/3100=33.33%.totally 100%, Answer is 2  

Question 3
A mixture of 20 L of spirit and water contains 5% water ,how much water must be added to this to raise the percentage of water to 24%? 
1. 5 Lt         2.4 Lt       3. 7 Lt       4. 8 Lt               5.10 Lt

Method 1
20 Lt mixture contains 5% water. Water content is 1 Lt. Spirit is 19 Lt. 
Let y be the liters water be added to make it 24%. 
Total quantity is 20 + y 
Percentage of  water  =>   { (1+y)/(20+y) }  x 100= 24       
 solve for y y= 5L

Method 2
Create a table 
  Sprit      water 
   19L 1L            Let x lit be added to the mixture. 
   19L       1+x 
Percentage of water must be 1+x=24%, 
so 19L sprit has to be 76%. 
   if 19L=>76% 
      (1+x)=>24% 
So (1+x) = 24 x (19/ 76 )= 6 x=5L 

 

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