Percent

• Percent is parts per hundred.
• 14% = 0.14
• 3/8 = 0.375 = 37.5%
• You should be able to change a fraction to a percent and a percent to a decimal number.
• Percent is also parts per whole.
• If I have completed 25% of a book with 130 pages, I have read how many pages?

  x pages read
  ---------------  = 0.25,      x = 130 × 0.25 = 32.5 pages
  130 pages total
     

• If I have read 50 pages of a book with 130 pages, I have read what percent?

     50 pages read
     --------------- = 0.384 = 38%
     130 pages total
     

• If I have read 92 pages of a book, and I am 42% of the way through, how many pages does the book have?

     50 pages read
     ---------------- = .42
     x pages total
  
     50 = x × .42
     50/.42 = x
     x = 119 pages
     

• If the old version of a text book has 527 pages and the new book has 12% more pages, how many pages does the new book have?

  
     New pages = 527 × .12 = 63 new pages
     Pages in new book 527 + 63 = 590 pages
     

• Percentage change

             New Value - Old Value
        PC =----------------------- 
                 Old Value
     

• If the PC is positive, it is a percent increase
• If the PC is negative, it is a percent decrease.
• A text book cost $120.00, The new version cost 152.00, compute the percentage change in the price

         152 - 120
         --------- = .27 or 27%
            120