Aptitude - Time and Work - Discussion

A = (1/20) * (80/100) = 1/25
1/A + 1/B =1/3(20/100)
1/B=(1/15) - (1/25) =2/75

thankx rajendra.........

For A
Here 80% work is done by A in 20 days.
so 80/20 = 4% work per day.
So,remaining 20% will take 20/4= 5 days.
so A will take 20+5= 25 days to complete 100% of work.
so A's 1 day work is 1/25 --------------(1)


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Similarly, remaining 20% is done by both (A & B) in 3 days.
so (20/3)% work per day.
Now, 100% work will be completed in 100/(20/3)
i.e. 100 x 3/20 =15 days.
(A + B)'s one day work is 1/15.
So,
A + B = 1/15
1/25 + B = 1/15
B = 1/15 - 1/25
SO B's one day work = 4/150 = 2/75
So B will take 75/2 days. i.e. 37 1/2 days.

@Bhaskar your explanation was superb. Carry on dude.

@Baskar you have done great job. Just carry on.

Thank you very much rajendra.

A does 80% in 20 days..so
A does 100% in 25 days..
A's 1 day work=1/25
A+B does 20% in 3 days..so
A+B does 100% in 15 days
A+B's 1 day work=1/15
1/25+B=1/15
B=1/15-1/25
B,s 1 day work=2/75
so B,s work=75/2 i.e 37 1/2 days..

@ baskar: thanks dude

For all friends..
work = days

for A:
80% work = 20 days
4/5 work = 20 days
cross mul
1 work = 5/4 * 20 days
1 work = 25 days
A's 25 days = 1 work ----------------------------->1

A+B remain work done in 3 days
total work = 1
80% work = 4/5
100% work = 1
100% - 80% = 1 - 4/5 = 1/5

for A+B:
work = days
1/5 work = 3 days
cross mul
1 work = 15 days
dat is

A+B's 15 days = 1 work --------------------------->2

now we know A's and A+B's work
now find B's work
apply A's in A+B's
A+B 1 Days= 1/15 works
A's 1 days = 1/25 works---->from 1..

1/25 + B = 1/15 works
B's days = 1/15 - 1/25 Works
B's days= 2/75 works
we have to calc works
cross mul
B's work = 75/2 days = 37 1/2 days

hey pls tell clearly ya its quite confusing