1. Sec. 4-4: Percent of Change

2. Percent of Increase or Decrease –
% = amount of change
original amount
i.e. Find the percent of decrease if a sweater that originally costs $29.99 is on sale for $24.99.
% = (29.99 – 24.99)
29.99
% =
% = .18 or 18%
*** Remember to convert decimal value to percent!

3. Greatest Possible Error –
One half of the “measuring unit”.
i.e. So, if you were measuring to the nearest inch, the greatest possible error would be a half inch.
If you measured to the nearest foot, the greatest possible error would be a half of a foot a.k.a. 6 inches.

4. i. e. Let’s say you want to carpet a room that is 7ft. by 13 ft
i.e. Let’s say you want to carpet a room that is 7ft. by 13 ft. and you want to make sure that the carpeting company does not over (or under) order the carpeting. What is the maximum & minimum areas? 7ft. 13 ft. EACH dimension would change by ½ a foot. To find area you multiply length and width so…. MAX. MIN. 7.5 (13.5) = sq. ft. (6.5)(12.5) = sq. ft.

5. 3. Percent Error – The percentage format of greatest possible error
3. Percent Error – The percentage format of greatest possible error. Percent Error = Greatest Possible Error Measurement i.e. Suppose you measure a table as 168 inches. Find the percent error in this measurement. Because you measured to the nearest inch, ½ inch is the Greatest Possible Error. % Error = .5/168 % Error = .003 = .3%