# Rethinking the Curriculum: Toward an Integrated, Interdisciplinary College Education

By Mary E. Clark; Sandra A. Wawrytko | Go to book overview

14 FORGOTTEN FUNDAMENTALS OF STEADY GROWTH

Albert A. Bartlett

INTRODUCING THE EXPONENTIAL FUNCTION

As a scientist, I happen to believe that the greatest shortcoming of the human race is our inability to understand the exponential function. The "exponential function" is the mathematical statement we write down to describe the size of anything that is growing steadily. If something is growing at 5 percent per year, the exponential function would show how large that growing quantity becomes, year after year. We are talking about a situation where the time required for the quantity to increase by a fixed fraction is a constant. So for 5 percent per year, the 5 percent is a fixed fraction and the year is a fixed length of time. That is what we want to talk about: ordinary, steady growth.

If it takes a fixed length of time to grow by 5 percent, it follows that it takes a longer fixed length of time to grow by 100 percent (to double). This longer time is called the doubling time, T2, and it is easy to calculate. You just take the number 70, divide it by the percent growth per unit time, P, and that gives you the doubling time.

For our example of 5 percent growth per year, we divide 5 into 70 and find that the growing quantity will double in size every 14 years. (The number 70 is roughly 100 times the natural logarithm of two, but just remember 70.)

-181-

If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items
Notes

#### Cited page

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

#### Cited page

Rethinking the Curriculum: Toward an Integrated, Interdisciplinary College Education

Settings

#### Settings

Typeface
Text size Reset View mode
Search within

Look up

#### Look up a word

• Dictionary
• Thesaurus
Please submit a word or phrase above.

Why can't I print more than one page at a time?

Help
Full screen
Items saved from this book
• Bookmarks
• Highlights & Notes
• Citations
/ 274

### How to highlight and cite specific passages

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

## Cited passage

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

## Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.