Latest IBM Aptitude Question SOLUTION: A does a work in 20 days. A did for 28 days. Then b came. They together take 76 days to complete the 7 job. Find howmany days B complete a work.

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A does a work in 20 days. A did for 28 days. Then b came. They together take 76 days to complete the 7 job. Find howmany days B complete a work.

Asked In IBM (12 years ago)

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Shishu Kamal  (11 years ago)

time for A to do one job IN 1 DAY= 1/20
time for A to do one job IN 28 DAY= 28/20
time for B to do one job IN 1 DAY= 1/B (LET)
SO,EQUATION A/Q:
28/20 + 76/20 + 76/B = 7
multiply by 20B BOTH SIDE:
1520 = 36B
B = 42.22 days to do one job alone

Is this solution Helpfull? Yes (18) | No (1)  

Anjali Tigga  (9 years ago)

In 20 days A completes 1 job. So,in 28 days A completes 1 2/5 job. Job left to be done is 7-(1 2/5) = 5 3/5 job. A and B work together for 76-28 = 48 days and complete 5 3/5 job. Let B completes work in B days i.e., rate of B is 1/B. A's rate is 1/20.
(1/20 + 1/B) * 48 = 5 3/5
=> 240 + 12B = 28B
=> 16B = 240
=> B = 15 days

Is this solution Helpfull? Yes (14) | No (4)  

Payal Dream  (10 years ago)

the ques is wrong ..if it takes A to complete the work in 20 days then in 28 days work will have already been completed..

Is this solution Helpfull? Yes (13) | No (7)  

uthra murugesan  (8 years ago)

http://www.algebra.com/algebra/homework/Rate-of-work-word-problems/Rate-of-work-word-problems.faq.question.625647.html

Is this solution Helpfull? Yes (2) | No   

uthra murugesan  (8 years ago)

does a work in 20 days. A worked for 28 days.
Then B came. Working together, they take 76 days to complete 7 jobs.
Find how many days it takes B to complete a work.
:
let b = time for B to do one job by himself
let one completed job = 1
:

%28%2828%2B76%29%29%2F20 + 76%2Fb = 7
104%2F20 + 76%2Fb = 7
multiply by 20b
104b + 20(76) = 20b(7)
104b + 1520 = 140b
1520 = 140b - 104b
1520 = 36b
b = 1520%2F36
b = 42.22 days to do one job alone

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