Time and Work Questions-2 | IBM Placement Papers

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. 

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?

Answer: 15 days

Solution:

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

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?

Answer: 40/9

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

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?

Answer: 5 + 5/11  hours

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

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?

Answer: 1/6

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

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

Answer: 12 days

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

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?

Answer: 225

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.

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?

Answer: 15/2 days

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

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?

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.