word prob: Beth can clean her house in 10 hours. When her hu

[billybob]

Beth can clean her house in 10 hours. When her husband helps, it takes both of them 6 hours. How long would it take Beth's husband working by himself?

 

[tkhunny]

Are you saying there was not a single example of this type of problem in your text book?

First, it requires a little thought. If Beth can do it in 10 hrs, it should take LESS THAN 10 hours if someone is helping - unless he is a bumbling idiot and messes things up faster than Beth can clean.

Where does that leave us?

 

[billybob]

No there is not an exapmple of this problem in my book, i've searched it cover to cover. Obviously, it takes less than 10 hours if they work together, it takes 6. That tells me nothing. I need a formula relating to work and time.

 

[skeeter]

beth's cleaning rate ... (1 house)/(10 hrs)

hubbie's cleaning rate ... (1 house)/(t hours)

together, their combined rate of cleaning is ... (1/10) + (1/t) houses/hour

[(1/10) + (1/t)](6 hours) = 1 house cleaned

solve for t.

 

[tkhunny]

No there is not an exapmple of this problem in my book, i've searched it cover to cover.

I do not doubt your conclusion, but you must see how odd that would be. Could you please list the Title, Author, Publisher, and Edition? I would be happy to pursue the publisher with some friendly advice.

You may be amazed at the number of folks who do not believe it obvious that the combined rate will be less than either single rate. It is a very common error that raises no consternation at all for many, many students.

 

[stapel]

No there is not an exapmple of this problem in my book....

That's extremely odd. Fortunately, there are many books on algebra word problems which will have entire chapters on this topic, and there are many lessons onlines which also cover the topic in depth. So you shouldn't have too much trouble finding some useful resources.

Eliz.