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

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