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Work Time Practice Question - CAT 2010 Prep

The question for the day is from the topic Work and Time. The problems from the topic are similar to those of Pipes and Cisterns. So, if you understand the nature of one of these two types of questions, then you will be able to attempt the other quite comfortably.

Question 5

Two workers A and B manufactured a batch of identical parts. A worked for 2 hours and B worked for 5 hours and they completed half the job. Then they worked together for another 3 hours and they had to do (1/20)th of the job. How much time does B take to complete the job, if he worked alone?

1. 24 hours
2. 12 hours
3. 15 hours
4. 30 hours
5. 18 hours
   
   

Correct Choice - (3). Correct Answer is 15 hours

Explanatory Answer

Let 'a' hours be the time that worker A will take to complete the job.
Let 'b' hours be the time that worker B takes to complete the job.

When A works for 2 hours and B works for 5 hours half the job is done.
i.e. . ....... (1)

When they work together for the next three hours, 1/20th of the job is yet to be completed.

They have completed half the job earlier and 1/20th is still left.

So by working for 3 hours, they have completed th of the job.

Therefore, ...... (2).

Solving equations (1) and (2), we get b = 15 hours.

CAT Practice Questions and Answers : Listed Topicwise

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