Percent Problems
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The document provides examples of solving percent problems using proportions. It explains that percent problems can be set up using the formula "is/of=%/100" and demonstrates solving for unknown values in word problems involving percentages of quantities and partial completion of a task over time. Sample problems are worked through step-by-step showing the set up of proportions and solving to find the unknown value.
Percent Problems
- 1. Percent Problems Monday, February 1, 2010
- 2. Repeat After Me… Is/Of = %/100 That, my friends, is the “Golden Rule” of percent problems. Another hint: the word “of” means to multiply!!!!!
- 3. What is 12% of 56? Remember….is/of=%/100. What do we know? We know the % is 12, of is 56, and 100 is constant. Set up the proportion….m/56 = 12/100. Now, cross-multiply and solve! 100m=672 m=6.72 So…6.72 is 12% of 56.
- 4. Word Problems!!! Members of the drama cub sold T-shirts for their upcoming musical. Of the 80 T-shirts sold, 55% were size medium. How many of the T-shirts sold were size medium? What do we know? Of=80, %=55, 100 =constant. Set up the proportion. n/80=55/100. Cross-multiply and find your answer!!!
- 5. Word Problem (continued) n/80 = 55/100 100n=4400 n=44 Therefore, 44 of the 80 T-shirts sold were size medium!
- 6. Yet another Word Problem… Loni has read 25% of a book. If she has been reading for 5 hours, how many more hours will it take her to complete the book? In this case, you should realize you’re look at part/whole (the part she’s read/the whole book) What do we know? is=5, of =unknown, % = 25, 100 is constant.
- 7. Yet another Word Problem (continued)… 5/r=25/100 *Cross-multiply 25r=500 *Divide to get r by itself r=20 It will take Loni 20 more hours to read the entire book.