Aptitude - Time and Work - Discussion

a : B = 13 : 10,
13 * 23 = x * 23.
x = 13.

The answer is approx 13 days.

As B would do the work in 230/7 days.
B's one day work would be 7/230.
a+b = x{1/23+7/230}=1.
x = apprx 13 days.

First, solve percentage i.e-30% = 3/10.

From that fraction, we can calculate the efficiency of both A and B which is 13 and 10.
Work=time x efficiency.
Total work =23x13
Time is taken by both to do the work=23x13/23,
=13 days.

Thanks @Abhishek.

B = (10+13/23)12.
B = (23/23)13,
B = 13.

A is 30% more efficient than B.

That means A=130% speed B=100% speed assume, then convert into ratio format because 13:10 it's work, now we can convert to days 10:13 (this ratio for separate man work days)

We must now ratio formula then only we understand,
This method.
A:B=A:B.
Also we write A:B::A:B.

Now apply
10:13::23:X ( Formula A:B::c:d =>A*d=B*c ).

Now we can solve that,
10X=13*23.
X=(13*23)/10.
NNow we got X value X =299/10 days for B.
B 1 day work is 299/10.
Then as usually go next steps.

Why should we consider only 100 and 130?

Let me assume supposed if A's efficiency is 100% then B's efficiency is 70%of A.

So,
Here given efficiency of A = 1/23
So B's efficiency is = 1/23(0.7),
= 7/230.

Now A+B work together;
So, 1/23+7/230.
= 17/230.

So the total no of days where A and B work together is 230/17.


Why isn't this answer is correct? plz, anyone explain.

A - 130.
B - 100.

130 23.
100 B.

130 * 23 = 100 * B,
130 * 23/100 = B.

A + B = 1/23 + 100/130 * 23.
= 130/130 * 23 + 100/130*23,
= 130 + 100/130 * 23,
= 230/130 * 23,
A + B = 1/13.