Aptitude - Time and Work - Discussion

Hi friends,

we know that whole work completed means we will denote it as 1(full)....

2=1(in 2days full work get completed)
5=1(in 5days full work get completed)
just simple 5=1/2 =>5*2=1(just cross multiple the 2)

1/5 of work being done in 3 days. But how do we arrive at the total no. Of days worked by A? what is the logic behind?

@benny-reli nice explanation.

1.)days worked by A is 2; 1 day helped by B and C and not A,
2.)given is A's 3 day work
3.)total 1 day work of A,B,C is find
4.)A's 2 day work is found
Result calculation:
A's 3day work=>(1/10)+(1/10)=>A 2day work+A,B,C's 1days)
=>1/5(of whole work) [5 is n]
A's whole work=3*5=15days

Thanks benny.

How can you taking that 3 days? and 1/10+1/10 what is it ?

Here 15 days is required for the completion of the work by A, B, C. But in question it is asked 'in how many days can A do the work' - which means the number of days A worked. So to get this we need to divide the 15 by 3 and get '5' as answer.

Can anyone please make me clear if my interpretation is incorrect ?

@Poornima

A works for 2 days and B,C joins him on 3rd day.
so total combination of them is now 3days
Based on these 3days we can furthur calculate..ok??
A's 2 days work=1/10 and on 3rd day A,B,C together work=1/10
So sum of them gives u total 3days of work done by all of them.

1st day A's + 2nd day A's work = (1/20 + 1/20) = 2/20 = 1/10--(1)

3rd day work is added by B's and C's work so, work done by A+B+C=

(1/20+1/30+1/60) = 1/10--(2)

from (1) and (2)= 1/10+1/10 =1/10

Answer explained:

A is working for 2 days alone so A's two day work is first calculated as
A's 2 day work is =1/20*2 = 1/10
Now B and C work with A for only one day(ie 3rd day) and A also working along with B and C in the same 3rd day so A,B and C one day work(ie 3rd day work) is calculated as=(1/20+1/30+1/60)=1/5

Now A's 2 day work+ ABC one day work(ie 3rd day work is calculated)= (1/10+1/10)=1/5
Therefore in 3 days only 1/5 of work is completed
Thus to complete full work 3*5=15 days
(3days=1/5 of full wok completed
3*5 days=full work completed
15 days = full work completed)