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# Aptitude - Time and Work - Discussion

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"Hold a true friend with both hands."
- (Proverb)
2.

A can lay railway track between two given stations in 16 days and B can do the same job in 12 days. With help of C, they did the job in 4 days only. Then, C alone can do the job in:

[A].

 9 1 days 5

[B].

 9 2 days 5

[C].

 9 3 days 5

[D]. 10

Answer: Option A

Explanation:

 (A + B + C)'s 1 day's work = 1 , 4

 A's 1 day's work = 1 , 16

 B's 1 day's work = 1 . 12

 C's 1 day's work = 1 - 1 + 1 = 1 - 7 = 5 . 4 16 12 4 48 48

 So, C alone can do the work in 48 = 9 3 days. 5 5

 Amit said: (Sun, Jan 2, 2011 12:05:31 AM) How the fractional 7/48 arrived?

 Gurjit said: (Sun, Jan 2, 2011 01:10:02 AM) Why did you write 5/48 as 48/5 ?

 Aparna said: (Sun, Jan 2, 2011 01:43:38 AM) @amit First solve the bracket, it is (1/16+1/12) First method: Simply you can do cross multiplication we get (12+16)/12*16 after solving we get 7/48 Second method: Find the lcm of denominators that's of 12 and 16 It is 48,and multiply it with each fractions i:e we get (3+4)/48

 Aparna said: (Sun, Jan 2, 2011 01:50:00 AM) @gurjit as per formula, If A's 1 day's work = 1/n , then A can finish the work in n days. here also same c's one days work=5/48 hence he can complete whole work in 48/5 days,tats asked to us and remember any fraction can also be written in quotient*remainder/divisor format when solved 48/5 quotient=9 remainder=3 divisor=5 hence, 9*3/5

 Bharathi said: (Thu, Jan 6, 2011 04:19:09 AM) How should know A, B, C work is 1/4.

 Geetha said: (Thu, Jan 6, 2011 08:56:31 AM) @Bharathi In ques they have mentioned that with the help of C they did the job in 4 days thatsy A+B+C=1/4

 Sowjanya said: (Fri, Jan 14, 2011 09:21:28 AM) Thanks geeta you solved my doubt.

 Reema said: (Sun, Jan 16, 2011 07:59:05 AM) How did 5/48 come explain it?

 Naresh Kumar said: (Tue, Jan 18, 2011 03:22:48 AM) Thanks Aparna and Geetha. You have solved my doubt also. I am very poor in solving such types of question.

 Shantanu said: (Wed, Jan 19, 2011 03:29:09 AM) Reema look A's 1 day's work = 1/16 because he took 16 days to complete the task similarly C's 1 day's work =5/48 so total no. of days will be 48/5

 Uthappa.U.K said: (Thu, Jan 20, 2011 11:49:49 AM) 1/4-7/48 cannot be equal to 5/48. Can anyone explain this to me?

 Jagan said: (Tue, Jan 25, 2011 11:10:56 PM) @ Uthappa 1/4-7/48 = ((48*1)-(7*4))/(4*48) //cross multiplication =(48-28)/192 = 20/192 //ok........ now its divisible by 4 =5/48 // r u got it?

 Neelam said: (Wed, Feb 2, 2011 01:05:20 AM) Thanks uthaap, I was confused about the cross multiplication. Now you explained in easy manner.

 Dinesk said: (Tue, Feb 8, 2011 02:45:15 AM) Nice aparna.

 Sathya said: (Sat, Feb 19, 2011 05:07:58 AM) @Shantanu. Your explain is very short and very sweet.

 Shalu said: (Fri, Mar 11, 2011 05:40:25 AM) @Aparna Why you substracted 1/4 -7/48 why dont you add 1/4+7/48 ?

 Sagar said: (Sat, Mar 19, 2011 12:02:16 AM) @SHALU SUPPOSE A,B,C ARE HAVING 10 RUPIEES WE KNOW DAT A=5 AND B=3 NW WE HAVE TO FIND C THEN WE WILL ADD BOTH A AND B AND REMOVE FRM TOTAL HERE ALSO SAME WE HAD DONE UNDERSTOOD

 Nalini said: (Sun, Mar 27, 2011 01:53:04 PM) @reema take lcm of 1/4 - 7/48 i..e 12-7/48 = 5/48:) got it??

 Mallik said: (Sat, Apr 30, 2011 01:09:06 PM) Reema explained clearly.

 Nikita said: (Wed, Jun 15, 2011 02:07:17 AM) 1/4= 1/12+1/16+1/c 1/4-7/48=1/c c=9*3/5 1/c= c's one day work

 Sunil said: (Sun, Jul 17, 2011 12:48:37 PM) Why 48/5 is written? please help me.

 Sunaina said: (Wed, Jul 20, 2011 08:52:50 PM) Why we should take 16 and 12 as 1/16 and 1/12?

 Karthick said: (Fri, Jul 22, 2011 01:28:27 PM) Why the fraction 5/48 is changed to 48/5?

 Shimpi said: (Thu, Jul 28, 2011 01:26:51 PM) Please help me in 1/4-7/48.

 Srikanth said: (Fri, Aug 5, 2011 07:17:52 PM) How 48/5 is written as 9*3/5 ?

 Sowmya said: (Fri, Aug 5, 2011 10:56:26 PM) @Srikanth 9*3/5=(9*5)+3=48/5

 Ravi said: (Sat, Aug 6, 2011 02:01:41 PM) Thanks uththapa. I get it.

 Saquib Ali said: (Fri, Aug 19, 2011 10:25:58 AM) You can solve all these sums very fast... a can do the work in 16 days b can do the work in 12 days c can do the work in x days Calc LCM of 16, 12 and x = 48x units of work in a day by a = 48x/16 = 3x units units of work in a day by b = 48x/12 = 4x units units of work in a day by a = 48x/16 = 48 units Total units of work in a day = 3x + 4x + 48= 7x+48 Thus in 4 days = 4(7x+48)= 28x+192 Total units of work=48x Thus, 28x+192=48x 20x=192 x=9 3/5 days.

 Meenakshi Dhawan said: (Wed, Sep 21, 2011 09:25:47 PM) @Saquib Ali. You have solved it wisely.

 Ovii said: (Sun, Sep 25, 2011 01:37:29 PM) @aparna Little help to the explanation of 1's days work. If A's 1 day work = 1/n than the complete/whole work can be done in n*1 days. It can be modify to above 1 day's work, e.g if A's 5 days work = 1/25, than the complete/whole work = 5*25= 125.

 Simran said: (Mon, Oct 17, 2011 11:53:47 AM) Thanks for the help.

 Vasudevarao said: (Thu, Nov 17, 2011 09:30:38 AM) Thank you nikitha well s. C method thanku.

 Swetha said: (Sat, Nov 26, 2011 03:10:25 PM) 1/12+1/16 =4+3/48 =7/48

 Chandrakant said: (Wed, Dec 14, 2011 12:37:56 AM) Wan we do it this way? A=16days B=12days, and A+B+C=4 days So 16+12+C = 4 i.e; 28-4 = c Hence c = 24days NOTE: Pls tell me if this method is correct, if not then why?

 Indian said: (Wed, Dec 21, 2011 01:13:04 PM) @ Ovii Thanks for explanation, Now I understood well.

 Tiny said: (Sun, Jan 15, 2012 12:27:14 PM) @chandrakant. Your method is totaly wrong. When c comes in right hand side it will become negative.

 Udita said: (Sat, Jan 21, 2012 12:07:20 AM) @Saquib Ali. Please explain the following step. Units of work in a day by a = 48x/16 = 48 units.

 Amrut said: (Mon, Mar 19, 2012 12:17:40 PM) C s one day work is 5/48. But how you came to 48/5, I mean C finish job in 48/5 days. Is there any formula for this result?

 Anshu said: (Sat, Mar 31, 2012 12:00:41 PM) "A" can do the 1/16 of the work in a day. "B" can do the 1/12 of the work in a day. A + b + c = 1/4 of the work. 1/16 + 1/12 + c = 1/4. 3/48 + 4/ 48 + c = 1/4. 7/48 + c = 1/4. C = 1/4 - 7/48 = 12-7/48 = 5/48. C can do 5/48 of the work per day. Therefore he can complete his work on 48/5 days = 9 3/5.

 Rajasekar said: (Wed, Apr 4, 2012 01:49:54 PM) How 5/48 is written 48/5?

 Suryakiran Varma said: (Tue, May 8, 2012 09:29:58 AM) Look, A can do a work in 16 days,so his one day work will be=1/16 and also B's one day work will be =1/12; in the same way A,B,C together do a work in 4 days,so thier one day work will be=1/4 C 's one day work will be=(A+B+C)'s one day work - (A+B)'s one day work i.e.. =(1/4)-(1/16+1/12) =(1/4)-(7/48) =(5/48) thus,C's one day work is = 5/48, so,he can do the work in 48/5 days..i.e..9 3/5.

 Hiren said: (Fri, Jun 8, 2012 11:02:06 AM) Why you write 48/5 from 5/48.

 Amit.J said: (Tue, Jun 19, 2012 11:04:51 AM) A+B+C=4 day. A=16 day. B=12 day. C=? Formula.. A+B+C=A*B*C/AB+BC+CA 4=192C/192+28C 4(192+28C)=192C 768+112C=192C 768=192C-112C 768=80C 768/80=C C=48/5 Ans.

 Parthasarathy said: (Wed, Jun 20, 2012 09:50:51 AM) @HIREN. If A can do some work in N days. So A can do that same work in one day =1/N. So the answer 5/48 obtained by (1/4) - (1/16+1/4) =5/48. So you should consider this as only 48/5.

 Pradeep said: (Sat, Jun 23, 2012 02:27:29 PM) Thank you aparna.

 Kalai said: (Thu, Aug 23, 2012 08:57:49 PM) I can't understand how 5/48 becomes 48/5. Can you clarify for me.

 Shiyamala said: (Wed, Aug 29, 2012 02:42:46 PM) A=1/16; B=1/12; A+B=[1/16+1/12] =[16+12/192]{1/16*12/12=16/192;1/12*16/16=16/192) =28/192 =7/48 {4*7=28; 48*4=192) C-[A+B]=1/4-7/48 {1/4*12/12=12/48) =12-7/48 =5/48 but c work alone.so,48/5=9*3/5

 Ajay Jabalpur said: (Sun, Oct 7, 2012 11:09:48 AM) @Hiren. If A's one day work = 1/n, then A can finish the work in n/1 days. Similarly, C's one day work is 5/48, then C can finish the work in 48/5 days.

 Twinkle said: (Sat, Jan 19, 2013 07:25:02 PM) A+B+C=1/4. [1/16]+[1/12]+C=[1/4]. C=0.1041. THEREFORE, 1/0.1041=48/5. i.e: 9*3/5.

 Sudha said: (Sat, Mar 9, 2013 07:08:14 PM) At the end of explanation, C's 1 day work is 5/48 I calculated up to to this but how it comes work in 48/5 days. Because acc. to formula if A's 1 day work is 1/n' then A can finish work in n' days. Means only it comes 48. I am just confuse. please explain me.

 Srinivas said: (Wed, Mar 27, 2013 06:38:35 PM) If I go for another way as follows: A B and C can do work in 4days. A alone 16 days. B alone 12 days. C alone ?... Lets assume it as X. Let me apply this formula Work done by A B and C put together i.e 4= (16*12*X)/(16+12+X) //(A*B*C)/(A+B+C). 28+X=48X. 28=47X. X=28/47. According To you Answer is Wrong How is it. Please Reply me As soon As possible.

 Sonu said: (Sat, Mar 30, 2013 11:08:13 AM) Why do we take fraction and add and subtract everything?

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