A teacher reports an average grade on a test.
You read about the average number of calories burned per hour for your favorite exercise.
What do these figures mean?
The purpose of this section is to discuss the concept, the computation, and some
important properties of averaging.
To average two numbers means to add the numbers together, and then divide by $\,2\,$. Thus:
Averaging two different numbers always gives the number exactly halfway
between, as illustrated below:
In this web exercise, you will compute averages of two
numbers, where the numbers can be
$\,10, 9, \ldots, 9, 10\,$.
You should be able to do this exercise without a calculator!
It is good practice with mental arithmetic, and will reinforce your skills with addition of signed numbers.
There are two key ideas to keep in mind:
Clearly, the formula
$\,\frac{a+b}2\,$
gives some number;
but how do we know that
the number given by this formula is really, always, halfway between
$\,a\,$ and
$\,b\,$?
Although repeated trials
(with lots of different numbers) is pretty convincing, it is of
course impossible to check every pair of real numbers.
To see a proof, read the text!
In this exercise, you must write your answers in decimal form (as needed).
That is, write (say) $\,2.5\,$, not $\,5/2\,$.
CONCEPT QUESTIONS EXERCISE:
On this exercise, you will not key in your answer.However, you can check to see if your answer is correct. 
PROBLEM TYPES:
