The focus of this PullOut is on
computing rates and average rates.
Calculations involving rates can
often be counterintuitive.
In Activity 1, the rate used is speed
(distance/time). Students discover
that the relationship between speed
and time when the distance is held
fixed is not linear. They also learn
that the arithmetic average of two
speeds does not always give the
correct average speed for a trip.
In Activity 2, the rate is fuel efficiency
(miles/gallon). Here students
discover that itâ€™s possible for a smaller
increase in fuel efficiency to result
in a larger savings in gasoline. In
Activity 3, the rate is batting averages.
Students are challenged to find
a situation in which one player can
have lower batting averages the first
and second half of a season compared
to another player, and yet have
a better batting average for the
season.
Mathematics prerequisites and
discussion:
Students should be familiar with the
concept of a rate. The rates used in this
PullOut are speed (miles/hour), fuel
efficiency (miles/gallon), and batting
averages (Number of hits/Number of
times at bat). They should be able to add
fractions or use a calculator to do so.
They should know how to calculate an
arithmetic average (for example, the
arithmetic average of 3, 6, and 10 is
(2 + 6 + 10)/3 = 6).
Materials needed:
Calculators.
