Aptitude - Time and Work - Discussion

All the explanations are really amazing and understandable. But I would like to add a point to the discussion. Why did we do 1/16, 1/12 or 1/4. See there is lot frequency distribution in the values. So to ease our lives we want to compare all this to a benchmark value.

In this case everybody is taking different number of duration's to complete a particular task. So first we want to find out how much work everybody was able to complete in any particular day. Just to make the calculations easier.

And if one can do (1/16)th part of a work in one day, then just by reversing the fraction we can get to know in total how many days he/she will be able to complete the entire task.

Hope this will help.

Please explain how come 5/48?

In equation 5/48 how did 5 arise?

Can anybody explain LCM method like this?

Lets see this simple method,

LCM of 16 and 12 is 48.

So A and B will finish their work in 3 and 4 hr.

Answer C will finish in 12 hr.

Hence 12-(3+4) = 5 hr.

Hence answer is 48/5.

Can anybody explain the basic to know how the 48/5 comes?

Why C-A+B?

Therefore C's 1 day's work = (1/4)-(1/16+1/20).

Can explain 5/48 has come?

How (1/16+1/20)?

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

Therefore 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 = 93 days.

@RaviKumar.

We have A+C = 4 -->A+C 1 day work = 1/4.

B+C = 4 --> B+C 1 day work = 1/4.

We add (A+C)+(B+C) = (1/4)+(1/4).

A+B+2C = (4+4)/(4*4) = 8/16 = 1/2.
A+B+2C = 1/2.
A+B+C = 1/(2*2) = 1/4.

That's it A+B+C = 1/4 -->A+B+C's 1 day work.

A's 1 day work = 1/16.
B's 1 day work = 1/12.
C's 1 day work = "We have A+B+C's 1 day work then subtraction to(A's 1 day+B's 1 day)".

= (A+B+C)-(A+B).
= (1/4)-(1/16+1/12).
= 1/4-(7/48) = 5/48.

C's 1 day work= 5/48 then C can do job= 48/5.

= Formula :: X 1 day task 1/n, x can do task n;

=48/5---> (9*5)+3/5---> 9 3/5.
=9 3/5.