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 =3/5×100=60% Similarly B takes 13 days to complete the work i.e B does 3/13th of the work =>3/13×100=23.3% C takes 9 days i.e C does 3/9th of the work= 3/9×100=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=>2/4×100=50% B takes 12 days=>2/12×100=16.66% C takes 6 days=>1/3×100=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

