Assignment
12

Investigation
12

Excel

This
data set is based on the first class letter postage for the US Mail from 1933
to 1996. Plot the data and develop a prediction function. When will the cost of
a first class postage stamp reach $1.00? when will the cost be 64 cents? how
soon should we expect the next 3 cent increase?

Answer:

Given

Plotting
the data:

As
you can see, it is an exponential function.

LetÕs
find a function that best fits the data by selecting Ôadd a trendlineÕ in
Microsoft Excel to display the best fit function.

So,
the function that best fits this set of data is

y
= 2E – 33e^{0.0394x}, where the x is the year and the y is the
cost of a stamp (in cents).

When
you add the current and future data to the data set above you get:

The
cost of a first class postage stamp will reach $1.00 in the year 2028.
The cost will be $0.64 in the year 2017. In 2010, we should expect a
$0.03 increase according to our prediction equation.