A, B and C can complete a piece of work in 24 days, 40 days and 60 day

Akela Although t+9 or t+7 wont matter but i think it should be t+7 (if u are assuming t days when A worked alone). please correct me if i am wrong

You're right, I misread statement 2. A worked t days, b worked (t-2) days, and c worked (t-7) days: t/24+(t-2)/40+(t-7)/60=1

Hi ,
This Ds question we do not need to solve completely. Let us start with info in hand. We know by given data that
A's one day work =1/24
B's one day work =1/40
C's one day work =1/60
Q: In how many days was the piece of work completed?

(1) A, B and C started working together, and A continued to work till the end.
As there is no info when B and C left the work so we can not say in how many days work was completed. Insufficient
(2) A, B and C started working together, B and C left the work 2 days and 7 days, respectively, before the completion of the work.
Start with info 2: here we know how many days B and c Worked and rest is done by A. Hence this is sufficient .

for those who want to solve: lets say in total t days work was completed.

A's t day work =t/24
B's 2 day work= 2/40
C's 7 day work =7/60

t/24 + 2/40 +7/60 =1 solve this equation to find value of t.

Thanks

Can u please tell me if my approach is correct or not and if I am solving it right or not?

A's one day work =1/24
B's one day work =1/40
C's one day work =1/60

Working together for first 2 days = (1/24 + 1/40+ 1/60) *2
A and C Working together for next 5 days = (1/24 + 1/60) *5
A working alone for rest of the days = (1/24)*x

(1/24 + 1/40+ 1/60) *2 + (1/24 + 1/60) *5 + (1/24)*x = 1

AND WE CAN FIND x by this?


Please tell me if i solved it right or wrong:?

Can u please tell me if my approach is correct or not and if I am solving it right or not?

A's one day work =1/24
B's one day work =1/40
C's one day work =1/60

Working together for first 2 days = (1/24 + 1/40+ 1/60) *2
A and C Working together for next 5 days = (1/24 + 1/60) *5
A working alone for rest of the days = (1/24)*x

(1/24 + 1/40+ 1/60) *2 + (1/24 + 1/60) *5 + (1/24)*x = 1

AND WE CAN FIND x by this?


Please tell me if i solved it right or wrong:?

I too arrived at C. How can I conclude A worked till the end using statement 2???

Hi Kezia9
I think you may have not read the second statement's complete sentence. The last part of the sentence states "Before the completion of work". Simplifying, you can say something like "X left 6 days before the completion of work" for example.

By this interpretation, since B and C left before completion of work, the only logical way to complete the work is when A stays till the end to complete the work.

Let's assume total days required was T days. Hence, A would have worked for T days, B for T-2 days and C for T-7 days. With this you can now form the equation and arrive at the solution, thereby making the statement 2 alone sufficient for this problem.

Hope my answer has helped you. Please leave a kudos in case you liked!

Hi Bunnel,

I have one doubt here, in st. (b) do we have to assume that A continued to work till the work was completed. Because it is always advised for DS qstns, never assume anything. My doubt arose because in st. (2) its not given that A continued to wrk till end, but if we combine it with st. (A) then we can confidently calculate no. of dys.

Kindly explain...Thanks

Hii,

You don't have to assume that because it is given that B & C lest before completion of work ... The question is How many days the work is completed ..It means the work has been completed for sure (100 %) ...& who has completed remaining work...?

Definitely A ..because he is the only remaining Person

I think the main issue with this problem is that the verbiage used is confusing. If we can assume that A continued to work until the end, statement 2 is sufficient.

Statement I
A, B and C started working together, and A continued to work till the end.
We dont know how many days B and C worked.
(Insufficient)

Statements II
A, B and C started working together, B and C left the work 2 days and 7 days, respectively, before the completion of the work.

Assume the total time taken to complete is t days.
i.e A worked for t days, B worked for (t-2) days and C worked for (t-7) days

Let's use fraction method to solve this question.
=>(t) x (1 / 24) + (t-2) / 40 +(t-7)/ 60 = 1

Solving this equation, we will get a value for t.
(Sufficient)

Option B is the answer.

Thanks,
Clifin J Francis

From statement 2, I also interpreted it not to conclusively say A was the one to complete the work. You can also see that the prompt didn't say A, B, C were the only ones working on the job. It just gives the work rates. You come across this in other DS problems where you're given the qualities of numbers to analyze (integer, even, etc.) and equations, but unless the prompt explicitly includes a number trait (if it doesn't say it IS an integer, you can't assume only integers), you can plug in any number that satisfies the descriptors. Why should we assume A, B, C were the only ones to work on the job if the problem doesn't explicitly say they are? Any ideas would be helpful, and thanks for the good discussions.