DUFAS Problem-Solving Method DIAGRAM made to show the problem. UNITS and variables listed and labeled on the diagram. FORMULA/EQUATION written and ready to use. ALGEBRA shown with numbers and units SOLUTION boxed/highlighted
Mrs. Chinners gives 5 points to students who earn 10 stars in her classroom. Suzy needed 15 pts on her test to pass! How many stars must she earn? Use DUFAS to solve this problem! 10
A proportion is a name we give to a statement that two ratios are equal. When two ratios are equal, then the cross products of the ratios are equal. cross products.
10 stars earned - 5 points on test is your given information. How many stars for 15 points? is your unknown. 10 stars to 5 points is you given ratio. this is a PROPORTION Problem. Diagram: list clues/draw
STARS Points Define variable: X = amount of stars needed for 15 points UNITS: listed &labeled
Proportions Formula/Equation a = c b d Formula/Equation
Cross Product: ad = bc 10 stars = X stars 5 points 15 points 10(15) = 5X 150 = 5X 150/5 = 5X/5 30 = X ALGEBRA (do the math)
10(15) = 5X PLUG IN X with value found. 10 (15) = 5(30) 150 = 150 Answer is Correct It takes 30 start to make 15 points! Solution: plug in and check!