Latest IBM Aptitude Question SOLUTION: A and B together can complete a work in 12 days. A alone can complete it in 20 days. If B does the work only for half a day daily, then in how many days A and B together will compl

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(#M40005523) IBM Numerical Ability question Time and work Keep an EYE

A and B together can complete a work in 12 days. A alone can complete it in 20 days. If B does the work only for half a day daily, then in how many days A and B together will complete the work?
A. 10 days B. 11 days
C. 15 days D. 20 days

Asked In IBM (12 years ago)

Unsolved Read Solution (8)

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Read Solution (8) :

rohit vashist  (12 years ago)

see ,
here given that A and B can do the work in 12 days
so A+B 1 day work = 1/12 unit.................................(1)
also given that , a alone can finish the work in 20 days
therefore
A 1 day work = 1/20 unit........................................(2)
using 1 and 2
we get,
B's 1 day work =1/12 - 1/20
=1/30..............................(3)
---> b can do the complete work in 30 days
now according to statement
if b does the work only half a day then it takes double days (i.e. 60) to complete the work
so now B 1 day work = 1/60.
also we know
A 1 day work = 1/20
now,
A+B 1 day work = 1/60 + 1/20
= 4/60
= 1/15 unit work
hence ,
A and B together will complete the work in " 15 DAYS " (answer)

Is this solution Helpfull? Yes (66) | No (7)  

sneha  (9 years ago)

A+B=1/12
A=1/20
B=1/12-1/20=1/30
A+B/2=1/20+1/(2*30)=1/15

Is this solution Helpfull? Yes (16) | No   

Dhananjay singh  (9 years ago)

Ur time is around 2 mint not 20 mint, follow this method

A completes the work in 20 days = 5% work done by A per day
A+B takes 12 days = 8.33% work done by both per day
Work done by B alone = 8.33-5 = 3.33 % per day
If B works half a day then contribution by B per day = 1.6%
Work done by both per day = 5+1.6 = 6.6 %
total days = 100/6.6 around 15 days

Is this solution Helpfull? Yes (4) | No (4)  

seema rana  (9 years ago)

ans is 15 days

Is this solution Helpfull? Yes (2) | No   

Manohar singh  (7 years ago)

a*b/(a+b)=12
20*x/(20+x)=12
20x-12x=240
x=30
i.e b=60
20*60/(20+60)=15
ans is 15

Is this solution Helpfull? Yes (1) | No   

AKAVARAM ROHIT REDDY  (6 years ago)

here given that A and B can do the work in 12 days
so A+B 1 day work = 1/12 unit.................................(1)
also given that , a alone can finish the work in 20 days
therefore
A 1 day work = 1/20 unit........................................(2)
using 1 and 2
we get,
B's 1 day work =1/12 - 1/20
=1/30..............................(3)
---> b can do the complete work in 30 days
now according to statement
if b does the work only half a day then it takes double days (i.e. 60) to complete the work
so now B 1 day work = 1/60.
also we know
A 1 day work = 1/20
now,
A+B 1 day work = 1/60 + 1/20
= 4/60
= 1/15 unit work
hence ,
A and B together will complete the work in " 15 DAYS " (answer)

Is this solution Helpfull? Yes (1) | No (1)  

Akshay Yadav  (8 years ago)

1/A + 1/B= 1/12
1/B + 1/C= 1/15

therefore,1/A - 1/C = 1/60
1/C=1/30-1/60 => 1/60

B = 20 days
C = 60 days
1/A+1/B+1/C=1/30+1/60+1/20=1/10
ans. 10

Is this solution Helpfull? Yes | No (4)  

Sandeep Chaudhary  (7 years ago)

C- 15days

Is this solution Helpfull? Yes | No   

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