Showing posts with label 8th grade math. Show all posts
Showing posts with label 8th grade math. Show all posts

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.