Solving Proportions
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This document outlines the three main steps to solve proportions: 1) Try using mental math or identifying a scale factor first. 2) If that doesn't work, simplify the fractions and try mental math again. 3) As a last resort, cross-multiply the terms and divide. It provides examples of using each method to solve proportions. The document concludes by explaining how to use a unit rate to solve a word problem about the cost of oranges by first finding the cost of one orange and then multiplying. Homework is assigned on proportional relationships from the textbook.
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Solving Proportions
- 2. Process for solving proportions: 1. Try mental math (scale factor) first! 2. If not, simplify the fraction given. Then try mental math again. 3. If not, then cross-multiply and divide! This method ALWAYS works.
- 3. 1. Use mental math (or scale factor) to solve a proportion. 36 21 12 x = x 28 21 14 =
- 4. 2. Simplify the fraction and then use mental math (scale factor). 15 x 10 8 =
- 5. 3. Sometimes you have to cross multiply and then divide. x 15 15 25 = (25)(x) = (15)(15) 25x = 225 25 225 25 x25 = x = 9
- 6. Solve this problem by finding a unit rate and then multiplying. If 6 oranges cost $2.34, then how much would 8 oranges cost? How would you find the cost of 1 orange? Then what?
- 7. Homework: P. 246-247 (1-5 all; 6-26 even) I made this into a WS for you. You still need to show ALL work for full credit!