### Amazon.com Selling Lots of Harry Potter Books

GDT has never looked at a Harry Potter book, but according to the Wikipedia "the Harry Potter books are a series of fantasy novels by British writer J. K. Rowling."

```   "Amazon.com announced that first-day pre-orders for 'Harry Potter
and the Deathly Hallows' were 547 percent higher than first-day
pre-orders for 'Harry Potter and the Half-Blood Prince' the sixth
book in the series."

"Amazon.com is currently selling 'Harry Potter and the Deathly
Hallows' for just \$18.89 (hardcover), a savings of 46 percent."
```

Assume zero knowledge of percents and percentages. Observe the following.

`100%` represents the "whole" of something. For example, if Zelmo ate `100%` of the pie, then he ate the whole pie. Percentages larger than `100%` arise when percentage differences between two numbers is used instead of amount differences.

```   5 increased 100% is 10
5 increased 200% is 15
5 increased 300% is 20
5 increased 400% is 25
5 increased 500% is 30
5 increased 600% is 35
```
##### Exercises
1. Pretend Amazon.com sold `5 copies` of the 6th Harry Potter book. `547%` increase implies they sold about `________ copies` of the 7th Harry Potter book.

2. Pretend a hardcover copy of "Harry Potter and the Deathly Hallows' is purchased for `\$18.89` at an Amazon.com store. No tax is charged. Paying with a twenty dollar bill will result in change of `\$_________`.

3. Pretend `15 hardcover copies` of "Harry Potter and the Deathly Hallows' for `\$18.89 per copy` at Amazon.com. No additional charges are applied (e.g. shipping is free, no taxes, etc.). The total cost of the purchase will be `\$____________`.

Creator: Gerald D. Thurman [gthurman@gmail.com]
Created: 02 February 2007