La Règle de Trois - Résoudre des Problèmes de Proportionnalité | Sixième - Collège

The rule of three is used to solve proportionality problems. Learn how to easily perform a rule of three! Chapter: Proportionality Year: Sixth Grade - Middle School Skill: Using the rule of three to solve proportionality problems See the summary sheet "_Using the Rule of Three to Solve a Proportionality Problem_" with practice exercises ► https://math-coaching.com/fiche/utili... Increase your mathematical power with _Math Coaching_, a math tutoring platform for French-speaking middle and high school students. Find on our website: Summary Sheets with interactive exercises. Private Tutorials online to benefit from personalized academic support. Learning Videos to progress at your own pace. Math Challenges that reward your efforts with gifts. WEBSITE ► https://math-coaching.com INSTAGRAM ►   / math.coaching   FACEBOOK ►   / mathcoachingfr   ----- The rule of three makes it easy to solve proportionality problems, like this one: The price of 9 pineapples is €36. What is the price of 11 pineapples? The first step is to note the relationship between the two values. This step requires no calculations! Start by drawing a horizontal arrow to connect the two proportional values. Write 9 pineapples to the left of the arrow and €36 to the right. The second step is to deduce the value associated with 1 unit. In this case, it's about finding the price associated with 1 pineapple. Draw a second horizontal line and mark 1 pineapple to the left of it. Your goal is to find the price of a single pineapple. To do this, observe the quantity of pineapples marked on the first and second lines. How much do you have to divide 9 by to get 1? You can move from the first to the second line by dividing by 9. Since the quantity of pineapples is proportional to their price, you can also divide the price on the first line by 9 to get the price on the second line. €36 divided by 9 equals €4. TADAM! The price of one pineapple is therefore €4. This is the magical principle behind the rule of three: when two values ​​are proportional, you can divide each value by the same number to obtain new values. Now draw a third horizontal arrow and write 11 pineapples to the left of it. The final step is to determine the price of 11 pineapples. Observe the quantity of pineapples noted on the second and third lines. By how much do you multiply 1 to get 11? By 11! So you can multiply the price in the second line by 11 to obtain the price in the third line. €4 multiplied by 11 equals €44. Congratulations! You have just solved this proportionality problem: the price of 11 pineapples is €44. You can use this rule of three to solve any proportionality problems that come your way. Remember that moving from one line to the next can only be done using multiplication or division. (c) Math Coaching - Academic support in mathematics (middle and high school)