Word Problems

[mathwhizwannabe]

1) Mary takes 20 minutes to wash and dry dishes after dinner. Eddy takes 30 minutes to do the same chore. How long would Mary and Eddy take to wash and dry dishes together?

2) Mary takes 20 minutes to read the daily newspaper. Eddy takes 30 minutes to read the newspaper. If they share sections of the paper, how long would Mary and Eddy take to read the newspaper at the same time?

3) Mary Takes 20 minutes to walk home from school. Eddy takes 30 minutes to walk home. How long would Mary and Eddy take to walk home from school together?

For 1) I got 12 minutes, which I think is right. (1/20 + 1/30 = 1/12; 1 divided by 1/12 = 12 minutes)

But I am not sure if I know how to do 2) and 3). Here is what I came up with so far...

2) 30 min (?) because it would take as long as it takes the longest person to read the newspaper

3) 24 min (?) (1/20 + 1/30 = 1/12; 2 divided by 1/12 = 24)

 

[Gene]

1) Exactly!

2) Ditto!

3) Whoops, this is the same as 2), not 1). If it had been like 1 you would still have whopsed. How did the 2 factor get in there?

 

[soroban]

Hello, mathwhizwannabe!

1) Mary takes 20 minutes to wash and dry dishes after dinner.
Eddy takes 30 minutes to do the same chore.
How long would Mary and Eddy take to wash and dry dishes together?

2) Mary takes 20 minutes to read the daily newspaper.
Eddy takes 30 minutes to read the newspaper. If they share sections of the paper,
how long would Mary and Eddy take to read the newspaper at the same time?

I believe #2 is the same as #1.
They are sharing the paper, reading different sections at the same time.
Maybe Eddy starts from the front of the paper, and Mary starts from the back.
When they meet somewhere in the middle*, the task is completed.

* They will meet at a point 2/5 of the way from the front.

3) Mary takes 20 minutes to walk home from school.
Eddy takes 30 minutes to walk home.
How long would Mary and Eddy take to walk home from school together?

Now <u>this</u> is a trick question . . . or a silly one.

It will take 30 minutes . . . because of Eddy.
. . (Mary would walk slower to keep him compny.)
There's no way to "combine" their speeds, you see.

 

[Gene]

Ambiguous, but I'll stick with my ditto. When my companion and I read a newspaper, we each read it all.
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Gene