Time And Work- Aptitude For All Exams

Time has always been an important tool for measuring the performance of a work. Completing a particular work in the given time frame is a must in today’s life. It is said that “Time is money”. Imagine, you are constructing a house with no estimate of time. Do you think that labours are going to finish it in minimum interval of time. The answer is no. They will be doing it in maximum period of time. Understanding time and work relation is very important.

Q. What is unit time work?

Suppose, a person is doing a work in N days where N can be number of days.In 1 day he has to do “1/N” work to finish the whole work in time.If you do your eat 10 banana in 10 minutes.  You will have to eat 1 banana in 1 minute. Similarly, if Ramesh does his home work in 2 days, he has to do ½ part of his home work in 1 day.

The work completed in unit time ( e.g 1 day) is called  unit time work.

Q. If A does a work in 10 days and B does the same work in 20 days. What is the total time in which they will complete the work working together?

ANS- A does work in 10 days.

          A’s 1 day work=1/10 part of work.

        B does work in 20 days.

       B’s 1 day work=1/20 part of work.

When A and B work together.

A+B’s 1 day work=A’s 1 day work + B’s 1 day work

                               = (1/10+1/20) = 3/20 part of work. [Shortcut:-To, get total time just reverse 3/20]                                                                                                                                              

 Since 3/20 part of work is done in 1 day

   Complete work (1 work) is done in {1/(3/20)}=20/3 days.

Method 2-(Simple Method)

Take the L.C.M of 10,20=20

Let us consider 20 unit of work is there to be done.

A’s I day work=2 unit work

B’s 1 day work=1 unit work

A+B’s 1 day work=(2+1)=3 unit work

3 unit of work is done in 1 day

So,20 unit of work is done in 20/3 day

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