Wednesday, December 2, 2009

Word problem on Time and Work

Some Important Facts about Time and work problems from answers to math problems

  • If A can do a piece of work in n days, then A's 1 day work = 1/n
  • If A’s 1 day’s work=1/n, then A can finish the work in n days
  • If A is thrice as good workman as B,then: Ratio of work done by A and B =3:1. Ratio of time taken by A and B to finish a work=1:3 , 

Let's see an example from 8th grade math worksheets

Question:-

Working together drew and joyce can put a futon frame together in 36 minutes.If it takes drew 60 minutes to put a futon frame together by himself.How long would it take joyce ?

Answer:-

Let us consider that joyce takes x min to complete it.

In 1 min he can do 1/x part of it.

Drew takes 60 min to complete the work

In 1 min he completes 1/60 part of it.

So, working together ,in 1 min they can do [1/x+1/60] part of it

It has given that together they can complete it in 36 min.

So ,together in 1 min they can do 1/36 part of it

So 1/x+1/60 = 1/36

So, x = 90 min

Which means joyce can put the frame together ,by her self in 90 min.

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