Math Is Fun Forum

sweetgyal

Guest

Average time

ok, this may seem simple to some of you, but... If Jane can paint a house in 4 hrs but John takes 6 hrs to paint the same, how long would it take them both to paint it together?

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: Average time

First, think about how much of a house they can paint in one hour.

Jane can paint 1/4 of a house and John paints 1/6 of it.
Therefore, working together they can paint 1/4 + 1/6 = 3/12 + 2/12 = 5/12 of the house in one hour.

This means that it will take them 12/5 hours to paint the whole house, otherwise known as 2 hours, 24 minutes.

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Why did the vector cross the road?
It wanted to be normal.

Sweetgyal

Guest

Re: Average time

Thank you, I really appreciate your help.  Math has never been my strongest subject and this is a great help.  Not all of us are gifted, so I'm thankful God gave that to some of you.

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: Average time

I would say that is perfect, and
I thought I'd mention that 1/4 + 1/6 is bigger than 1/3.
Because 1/2 - 1/6 is 1/3.  This is off the subject a little.
And 1/3 = 1/4 + 1/12, and 1/12 + 1/6 = 1/4,
And so for this problem 1/4 + 1/6 is 1/2 - 1/12 = 6/12 - 1/12 = 5/12
Nice job, mathsy!!!
I love it when a plan comes together.

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