If the first chapter of a certain book is 28 pages long and makes up 4% of the book, how many pages does the entire booo have?

Answer 1

Set up a RATIO EQUATION.

28 pages is to the number of pages, P, and

4 is to 100, since 4% means 4 divided by 100.

28/P = 4/100

Most don't teach what I am about to show you. But it ALWAYS WORKS, and is VERY EASY TO REMEMBER.

JUST CROSS MULTIPLY! (Cross multiply the numerator times the denominator of both sides of the equation.)

In this example CROSS MULTIPLICATION means multiply P times 4, and set that equal to 28 times 100.

(4) (P) = (28) (100)

(4) (P) = 2,800

P = 2,800/4 (Dividing both sides by 4.)

P = 700 Pages

THERE ARE 700 PAGES IN THE BOOK.

CHECKING:

10% of 700 pages = 70 pages

1% of 700 pages = 7 pages

4% of 700 pages = 4 x 7 = 28 pages

OR: .04 x 700 = 28