Aptitude - Time and Work - Discussion

How come 4/90? I don't understand.

First thing, the work done is always same, i.e. Work done by A = work done by B = work done by A+B.

So, if A does a work in x days then B does it in 60-x days.

Now, we can write A=3B

So, work done by A will be = 1*x = x
Work done by B will be = 3*(60-x)

As we know work done remains same then

x = (60-x)*3.
x = 45,

So, A's total time = 45.
B's total time = 60-x = 60-45 = 15.

So, now we can find the total time taken by A+B to complete the work as,
1/15 + 1/45 = 4/45.

It's one day work of A+B so reciprocal it to get the total time taken by them.
45/4 = 22.5 days

(3-1)=2------>60
1------>30
3------->90.

1's day work for A= 1/30
1's day work for b=1/90
Both 1's day work=(1/30+1/90)
= 4/90.

Total day = 90/4.
= 22(1/2).
The answer is B.

We can simplify it.

Assume if B worked for 90 days and
C worked for 30 days.

B's 1-day work = 1/90.
A's 1-day work = 1/30.

A+B = 4/90 work.
ie, 90/4 = 22.5.

(T*T.D)/(T^2-1).

T-EFFICIENCY.
T.D-TIME DIFFERENCE.

So;
3*60/9-1 = 22.5.

Let's assume A completes its work in x days.

B completes in 3x days . since A is times efficient than B.
now, their difference is 60 days.
then, x-3x=60,
2x=60,
x=30,
A=30,B=90.

So, one days work of A and B together is A+B=1/30+1/90.
=4/90,
=2/45,
So one day work of A and B together is 2/45.
So A and B can complete the work in 45/2 days.
this equals to 22(1/2).

What is wrong with the below step?

A's 1-day work = 1/y.
Then, B's 1-day work = 1/3y.

Now,
A completes work before 60 days compared to B.

So,

1/y - 1/3y = 1/60
2/3y = 1/60
y = 40.

i.e., A completes in 40 days and B completes in 120 days,

Now, working together they complete in
1/A + 1/B = 1/40+ 1/120 = 1/30.

So, Together they complete in 30 days.

A and B
Work 3:1
Time 1:3
i.e. 30:90 ......multiply by 30.

And also they have given that the difference between the time taken to complete the work is 60.

Hence when A and B time to work together,
1/30+ 1/90 = 2/45,

Defer for A and B to complete the entire work they require 45/2 which is equivalent to 22 and A half-day.

Hi, friends, it's a bit tricky.

First, they found the time difference to do work between a and b.
Because the data we have is time difference in qn for 60 days consider.

Then. If a takes 1 day. B takes 3 days. So.

For 2 days time difference : 3 days for b

Then multiply both sides by 30 since the time difference is given

For 60 days time difference: 90 days of b.

I hope you all get it.

Then use ratio. A takes 30 days to complete work.

Please tell how A is working 30 days. How we calculate I don't understand.