Aptitude - Time and Work - Discussion

A= 80% in 20 days.
100% in 25 days.

A + B = 20% in 3 days.
100% in 15 days.

LCM OF 15 and 25 is 75.

Efficiency of A is 75/25 = 3.
Efficiency of A+B is 75/15 = 5.

A+B = efficiency of A+B is 5 so that,

A+B = 5,
3+B = 5,
B = 2.

THEN 75 IS TOTAL WORKS.

So, 75/2 = 37.5.

Thanks @Karan.

80%--->20days.
20%--->'x' days.
x = [20 * 20%]/80%.
x = 5 days.
1/5 + 1/y = 1/3.
1/y = 2/15.
20%--->15/2 days.
100%--->'z' days.
z = [(15/2) * 100%]/20%.
z = 75/2 days.

@Rajendra.

Thank you for explaining.

A = 80% in 20 days.
80% = 80/100 = 4/5.
A = 4% Daily work.

80-100 = 20% of work remaining.
20% of work done by A+B in 3 days.

A = 4% Daily work in 3 days.
A = 4×3=12%.
20 - 12 = 8%.
B = 8%.
B = 8/100%×3 = 37.5 = 37 1/2.

Finally, I understood the concept, Thanks @Rajendra.

A = 20/(80/100)=20/(4/5)
A = 20*5/4.
A = 25 days i.e 1/25 days.
1-(4/5 )work is done = 1/5.
A+B = 1/15.
1/15 - 1/25 = 2/75.
75/2 i e 37(1/2) days.

A can do 80% of work in 20 Days.

So, 20 days = 80%,
1 day = ?
= 4%,

A and B worked for 3 days so 4% A can do in 1 day and in 3 days it is 3*4=12%.
A and B together worked and completed the remaining 20% of the work in 3 days which A work is 12%.

So, A+B =20%,
12% +B =20,
B = 8%,
B worked 8% in 3 days,
3 days = 8%,
1 day = ?
=2.66%.

The whole work is 100% in itself,
B 100/2.66 ==37.5 or 37 1/2.

@All.

Here A do 80% work in 20 days.

That mean remaining work = 20%.
On diving 80 by 20 = A do 4% work in 1 day
So the remaining 20 % has to be done in 20/4 =5 day.

Now, total days were taken by A = 20 + 5 = 25.
Now, ACC to question;

A+B Takes 3 days to complete the remaining work so 5 * 3 = 15 days.
Now;
A= 25,
A+B=15.

On taking LCM we get 75.
So now by dividing,
A's efficiency = 75/25 = 3,
A+B efficiency= 75/15=5.

Now B efficiency = 5-3 = 2 bcz A+ B= 5 nd A=3.
Now dividing B efficiency from total working days = 75/2 = 37.5.

In the case of A,

80 %. = 20 days
So
100% = ?

Cross multiplication
= 100 *20 /80
= 25 days.

So, A has the power to do daily;
100/25 = 4 % of the work.

As given
80 % of the work is done by A,
for the Remaining 20% of work, he calls B to finish work in 3 days.

In 3 Days, 'A' worked by using his power of 4% and did 4* 3 = 12

The remaining 20 -13 = 8 % will be completed by 'B' in 3 days
B' will work,
8 %. = 3 Day
100% =. ?

Crossing
= 100* 3/8
= 75/2,
= 37.5
And the answer is 37 and a half means i.e. 37 1/2.