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MJ2 Ch 8.2 – The Percent Equation 1. Figure EFGH and ADCD are similar. The ratio of their corresponding sides is 1:2. What is the length of EF ? H B G E 3 . F ? 1 n 2 7 C A 7cm 2n = 7 1 n 3 cm 2 D • 0 1 2 3 4 5 6 7 8 9 / • 0 1 2 3 4 5 6 7 8 9 5 / • 0 1 2 3 4 5 6 7 8 9 / • 0 1 2 3 4 5 6 7 8 9 • 0 1 2 3 4 5 6 7 8 9 Bellwork – You do not have to write the question Before we begin… • Please take out your notebook and get ready to work…. • In today’s lesson we will continue with the chapter theme of applying percents…more specifically, in today’s lesson we will look at the percent equation, which is a formula… Objective • Students will solve problems using the percent equation. The Percent Equation • The percent equation is a variation of the percent proportion…the big difference is that in the percent equation the percent is expressed as a decimal. • The percent equation uses the following formula part = percent ● base Using Formula’s • Whenever you work with a formula you are to use the following strategy… 1. Write the formula 2. Substitute 3. Do the math • • You must show each step…and rewrite the equation after each operation At this level you are required to demonstrate what you know….this is how you do that! Example • What number is 12% of 350? • Before I begin…I have to know some stuff…like… • 12% expressed as a decimal is 0.12 • 350 is the base • I need to find the part, which I will call n.. • Now…lets work it out using the formula method… Example… part = percent ● base n = 0.12 ● 350 n = 42 • Therefore, 42 is 12% of 350 1. Write the formula 2. Substitute 3. Do the math How to identify the parts of the percent equation • Most often these types of problems are word problems… • Key phrases tell use what they are looking for as follows: To find the part you might have a question like this What number is 50% of 6? To find the percent you might have a question like this 3 is what percent of 6? To find the base you might have a question like this 3 is 50% of what number? Your Turn • In the notes section of your notebook write the expression and then use the percent equation to solve 1. 21 is what percent of 40? 2. 12 is 26% of what number? 3. What number is 88% of 300? Summary • In the notes section of your notebook summarize the key concepts covered in today’s lesson • Today we discussed: • The percent equation • What is the formula? • How can you tell what the part, base and percent are? Assignment • Text p. 342 # 8 – 24 Reminder • This assignment is due tomorrow • I do not accept late assignments • You do not have to write the question. However, you must use the formula method, step by step, to solve each problem. • You must show your work (no work = no credit)