Associated Topics || Dr. Math Home || Search Dr. Math

A Cat Word Problem

```
Date: 08/23/2001 at 00:52:09
From: rachel
Subject: Word problems

Hi,

I am bad at word problems - I don't understand how to take out the
infomation you don't need. Here's the problem:

You have 5 cats and they all are 6 and all weigh 10 pounds. How much
do they weigh altogether?

What do you take out?
```

```
Date: 08/23/2001 at 13:02:02
From: Doctor Peterson
Subject: Re: Word problems

Hi, Rachel.

The way to decide what information you don't need, is to list all the
information you have, and all the information you DO need. To find
what you do need, you'll need a plan for solving the problem. And that
idea of planning is probably the main point of this sort of exercise.

What do you know?

There are 5 cats.
Each cat is 6 (years old?).
Each cat weighs 10 pounds.

What is the goal?

How much do they weigh altogether?

How can you find that out? You know the weight of one cat, and how
many cats there are, so you can multiply. That's your plan. (You can
often make a plan by just taking one fact and thinking about what you
could do with it, then seeing if any other facts will help. When you
find a way to the goal, you can retrace your steps and see which facts
you used.)

Now you can check off the information you used in your plan; that will
leave one item that is not needed, and that is the answer to the
problem.

It's entirely possible that you might have a different way to solve
some problems than your teacher would, so you might come up with a
different answer that would still be valid for your method of solving
it. Usually a problem like this will be pretty straightforward; but in
real life, there might be several tricks you could use - sometimes you
have redundant (extra) information, and can choose to take the short
way (using the best information you are given), or the long way (using
a different set of information), or the safe way (using both methods
and comparing).

weigh four pounds when they are born, and gain one pound a year for
the first ten years. Then if you want to take the long way, you could
figure out for yourself that each cat weighs 10 pounds; you would be
using all my new information, but would not need to have been given
the cats' weight.

I myself tend to want to use all the information I am given, in order
to check that it all agrees. If we had been told that each cat weighed
12 pounds, we would have inconsistent information, and would know we
had to go back and check the numbers we were given. So in real life,
there may be no information you WON'T use, even though there is some
you don't HAVE to use.

If you do well in all subjects except math, you can use your other
abilities to strengthen your math skills. Problem solving, you may
have noticed, involves more than just numbers. It requires a good
understanding of language, an ability to imagine yourself in a
situation, and perhaps even some background information about cats or
whatever. If you ever read mystery books, they are all about problem
solving. Which of the facts the detective knows are useful, and which
are "red herrings" that are only there to confuse you? That's the same
thing you're doing here. You might find you can improve your problem-
solving skills by not thinking of it as math, but as fun! Be a
detective, and look for different ways to think through a problem.
Eventually, you'll find that all math is really problem solving, and
is fun if you look at it the right way.

- Doctor Peterson, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
Elementary Word Problems

Search the Dr. Math Library:

 Find items containing (put spaces between keywords):   Click only once for faster results: [ Choose "whole words" when searching for a word like age.] all keywords, in any order at least one, that exact phrase parts of words whole words

Submit your own question to Dr. Math
Math Forum Home || Math Library || Quick Reference || Math Forum Search