The Time and Work section is very important for IBM placement preparation. Practice and Learn questions on Time and Work topic important for IBM placement aptitude test.

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Question: 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?

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Answer: 15 days

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Solution:

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A+B=1/12

A=1/20

B=1/12-1/20=1/30

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

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Question: Worker A takes 8 hours to do a job. Worker B
takes 10 hours to do the same job. How long should it take both A and B,
working together but independently to do the same job?

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Answer: 40/9

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Solution: one day work of A = 1/8

one day work of B = 1/10

so one day work of A and B together = 1/8 + 1/10 =
9/40

so total days required = 40/9

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Question: P can complete a work in 12 days working 8 hours
a day,Q can complete the same work in 8 days working 10 hours a day. If both P
and Q work together, working 8 hours a day, in how many days can they complete
the work?

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Answer: 5 + 5/11 hours

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Solution: First we have to convert into hours it is easy to solve the question

so p ==> 12 * 8 = 96 h

Q ==> 8 * 10 = 80 h

p+Q= 1/96 + 1/80 = 11/480

(ie) 480/11 h

per day 8 hours so 480/11*8 = 60/11 days (ie) 5
5/11 days

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Question: A can finish a work in 18 days and B can do the
same in half the time taken by A. Then, working together , what part of the
same work they can finish in a day?

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Answer: 1/6

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Solution: In one day A can finish work in 1/18 days

similarly B`s work is 1/9 days (since B=half time
taken by A)

working together = 1/18+1/9=1/6

So answer is 1/6

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Question: A takes twice as much time as B or thrice as much
time to finish a piece of work. Working together, they can finish the work in 2
days, can do the work alone in

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Answer: 12 days

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Solution: Suppose A, B and C take x, x and x days respectively to finish the work.

2 3

Then, 1 + 2 + 3 = 1

x x x 2

6 = 1

x 2

x = 12.

So, B takes (12/2) = 6 days to finish the work

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Question: 10 men and 15 women together can complete a work in 6 days. It takes 100
days for one man alone to complete the same work. How many days will be
required for one woman alone to complete the same work?

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Answer: 225

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Solution: 1man 1 day= 1/100

(10man+15woman) 1day = 1/6

10/100+15woman1day = 1/6

15 woman 1day = 1/6 - 1/10

1 woman 1 day = 1/15 (1/6 - 1/10) = 1/225 = 225ans.

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Question: Four skilled workers do a job in 5 days, and five
semi-skilled workers do the same job in 6 days. How many days will it take for
two skilled and one semi-skilled worker to do that job?

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Answer: 15/2 days

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Solution: 4 skilled in 5 day

2 .......... 10 day

5 semi-skilled in 6 days

1 ............... 30 days

2 skilled & 1 semi skilled in one day = 1/10 +
1/30 =2/15 work

hence, 2/15 work in 1 day

so, 1 work will be 15/2 days Ans

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Question: If 20 men or 24 women or 40 boys can do a task in
12 days working for 8 hours a day, how many men working with 6 women and 2 boys
take to do a task four times as big working for 5 hours a day for 12 days?

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Answer: 122 days

Solution: Amount of work done by 20 men = 24 women = 40
boys or amount of work done by 1 man = 1.2 women = 2 boys.

20*12*8/1=m*12*5/4

m=128

6 women are the equivalent of 6/1.2 = 5 men and 2 boys = 1 man.

he equivalent of 5 + 1 = 6 men are already working on the project.

then 128-6=122

Therefore, 122 more men are required to work with 6 women and 2 boys to complete the task.

20*12*8/1=m*12*5/4

m=128

6 women are the equivalent of 6/1.2 = 5 men and 2 boys = 1 man.

he equivalent of 5 + 1 = 6 men are already working on the project.

then 128-6=122

Therefore, 122 more men are required to work with 6 women and 2 boys to complete the task.