Aptitude - Time and Work - Discussion

@All.

A is 1st-day work 1/20.
A is 2nd-days work 1/2.
02/20.
a+b+c together work is = 1/20 + 1/30 + 1/60.

Add 2/20+1/20+1/30+1/60 = 1/5.
For 3 days = 1/5 * 1/3 = 1/15 ie 15 days.

A=30
B=20
C=60

Now take the lcm that is 60 mean A will make 3 chairs for example in one day B will make 2 chairs in one day and will make c will make 1 chair ( chairs example is for understanding).

Now A will make 3 chairs in one day and after 3 days it will make 9chair ( 3 *3) and at the third day ( B +c) will also make 3 chairs mean at the third day A +B +C WILL MAKE 12 chair in 3 days to make 60 chairs which our lcm it will require 15 days ( 12*5 = 60) that is 3*5 is 15 days.

Why 3 is multiplied by 5 in the last step? Please tell me.

Please explain the 3rd step.

How it is 3*5 at last?

A's 1 day work is 1/20, B's one day work is 1/30, C's one day work is 1/60.

Given problem A is doing 2 days work alone and assisted B&C on the third day and repeats this cycle.

So, the Total work done in 3 days= (A's 2days work) + (A+B+C's 1 day work) i.e., (1/20x2) +(1/20+1/30+1/60).

(1/10) +( (3+2+1)/60) (hence 20,30,60 lcm is 60),
=> 1/10+(6/60),
=> 1/10+1/10 = 2/10=> 1/5.

Here the work done in 3 days is 1/5;
So total days required is 3x5=15.

Efficiency total work-60.

A - 20 days----> 3
B - 30 days----> 2
c - 60 days-----> 1

A+B+C work=6---->3 days work=12.
The total work to done is 60 hence 12 * 5=60.
Hence days are 5 * 3=15 is the right answer.

First, we took lcm of all 3 that is A, B and C that is 60. On the basis of this A's efficiency is 3, B's efficiency is 2 and C's 1. So first 2 days A will do the work that is 3x2=6. Third-day work will be 6 as all three are doing the work. So 3 day's work will be 12. On the basis of the unitary method in every 3 day, they are doing 12 work so 3 day's efficiency will be 4unit. So, total work that is 60 divide by 4= 15.

That is 1/15 work is done in 1 Day.
Now 4/5 part of work that is (1-1/5) will be done in :15*4/5 =12 days.

In 3 days ,the total work = 3/20 + 1/30 + 1/60 = 1/5.
1/5 % done in 3 days.
1% done in 3/(1/5) = 3 * 5 = 15 days.