# The IntMath Newsletter - July 2007

By Murray Bourne, 15 Jul 2007

You are receiving the IntMath Newsletter because you signed up, asked a question, wrote a comment or complimented Interactive
Mathematics.

======================
1. This month's math tips
2. What's new
3. Latest Poll
4. From the math blog
======================

## 1. THIS MONTH'S MATH TIPS

a. How to make the most of it
Many of you have used the 'Comments? Questions?' facility in Interactive Mathematics to ask your homework questions. I enjoy
helping you out.

Some students genuinely want to know how to do the homework problem, but some students write something like:
'PLEASE MAIL ME THE WHOLE SOLUTION OF THE QUESTION.

Now I could do that, and the student would copy my solution into their homework assignment. They would get a good grade, but how can I know that they actually understood it, or if they could do a similar problem all by themselves? Have I really helped them to develop their skills and understanding?

Instead, what I do is help them to get started on the problem by giving the first step and directing them to a page that will help them to figure out the rest. Then we usually exchange emails while they work it out and get my assurance that they have done
it properly.

That's the way it should work.

b. Will a forum help?
this mail with your thoughts on this.

c. Take care of the UNITS
Many students struggle with units in maths problems, especially where it involves multiplying, dividing or converting units
(like km/h to m/s).

Let's do an example. Many physics problems require an answer in m/s but maybe we measured in km/h. Say we observe someone
walking at 6 km/h. How many m/s is that?

Estimate first: We know that a slow walk is about one meter each second (try it). A fast walk is 3 m/s (try it). Our final answer should be in the range 1 to 3 m/s.

It's best to convert one thing at a time. You could proceed as follows.

6 km/h = 6000 m/h (I have written 'km' as '1000 m'.)

Now, divide both '6000 m' and 'one hour' by 60 and we get 100 m/min.

Finally, divide both '100 m' and 'one minute' by 60 and we get 1.67 m/s. So 6 km/h equals 1.67 m/s.

Estimating first is very worthwhile and it helps you understand the concept better.

Here's another example from the world of aviation. Airlines need to consider many costs, like fuel, food, salaries, maintenance
and so on. One of the quantities that they deal with involves the number of passengers multiplied by the amount of time those
passengers spend on an aircraft.

So for example, if we have 120 travelers and they are on a 3 hour trip, the correct way to write the answer for
(120 travelers) x (3 hours)
is
360 traveler-hours

Always take care of the units...

## 2. WHAT'S NEW IN INTERACTIVE MATH

a. Writers of computer games use a lot of mathematics. At the bottom of each page on the IntMath site you will see some games which all involve mathematics in some way. The most popular one is ShadowFactory.

b. There are now math quotes at the bottom of each page - to
inspire (or amuse) you.

## 3. LATEST POLL

What is the best time of the day for you to study mathematics?
If you haven't voted in the poll yet, go to any page on the Interactive Mathematics site and you'll see the poll in the right hand column. The answers so far tell us a lot about the worst times to conduct math classes...

See the results of previous polls.

## 4. LATEST FROM THE MATH BLOG

1) ISAAC NEWTON LOSES HIS FORTUNE
Isaac Newton lost buckets of money in a stock investment crash.

2) A SIMPLE CLIMATE CHANGE MODEL
What are the variables that go into a climate model?

3) MATH IN COMPUTER GAMES
see how mathematics is an important part of games development.

4) AUSTRALIA'S TOP CHINESE WEBSITES
The changing face of Australia: Chinese websites are popular Down Under because of immigration from China and there are an
increasing number arriving from India as well.

5) COMPARING CURRENCIES: STREET PRICE OF COCAINE
One way of comparing the value of world currencies is via the price of cocaine in different countries.

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