Help with Real, Natural, Whole, Integers, Rational, and Irrational Numbers?

Question

My math homework has these 2 questions that I am confused with. The directions say "Which set of numbers describes the values of each variable?"

The first question says, "The high, H, and low, L, for a certain stock period during a period of N weeks."

The second question says " The average time per lap, T, it takes a race car to complete N laps."

I know what those kind of numbers are, I just don't know which group would best describe those questions.

Answer 1

Stock prices are in dollars and cents.

Sometimes even fractions of cents, too.

In any case, dollars and fractions of dollars -> Rational numbers.

(Whether or not stock prices themselves are rational

is a subject for the Finance or Psychology sections.)

Race times are in seconds (or higher time units)

and fractions thereof.  Again -> Rational numbers.

These are also real numbers, but presumably the desired

answer is the most restrictive.

Natural, Whole, and Integers are ruled out,

unless some micro-unit is used, which it usually isnt.

(If you determined that the smallest unit of stock price

was 1/10000th of a cent and expressed everything as

a whole number of those, then Integers would be used.

But that doesn't happen.

Similarly race times are not expressed as whole numbers

of microseconds. Even then, after dividing by number of

laps, you might still have a fraction.)

.

Answer 2

Use the following order

Natural

Whole

Integers

Rational

Real

Each set is a subset of the one following.  Use irrational only if necessary.

Part 1)

Look at the stock pages.  The high and low are normally listed as

5.1234 and 1.2031 or some such.  I would call these Rational.  

N weeks is a number from 1 to large, so use Natural

Part 2)

Time is continuous, so I would use Real

N laps is, of course Natural