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Warm Up. Problem of the Day. Lesson Presentation. Lesson Quizzes. Agenda for Mar. 7, 2011 Bellwork Florida Ready Lesson # Lesson: 6-7 Simple Interest Classwork : 6-7 Practice It! Worksheet H/L : 6-7 Complete Practice It! (worksheet) 6-7 Simple Interest (thinkcentral)
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Warm Up Problem of the Day Lesson Presentation Lesson Quizzes
Agenda for Mar. 7, 2011 Bellwork Florida Ready Lesson # Lesson: 6-7 Simple Interest Classwork: 6-7 Practice It! Worksheet H/L: 6-7 Complete Practice It! (worksheet) 6-7 Simple Interest (thinkcentral) Ch. 6 Section B Quiz (thinkcentral)
Warm Up Multiply. 1. 800 0.04 3 2. 1,700 2 0.25 3. 900 0.05 4 4. 1,200 6 0.35 96 850 180 2,520
75 3 4 3 40 = ; the others equal . 1,000 Problem of the Day Which number does not belong in the group? 0.75 75% 3 4 6 8 75 1,000
Sunshine State Standards MA.7.A.1.2 Solve percent problems, including problems involving…simple interest…
Vocabulary interest simple interest principal
When you keep money in a savings account, your money earns interest. Interest is an amount that is charged for borrowing or using money, or an amount of money that is earned by saving money. For example, the bank pays you interest to use your money to conduct its business. Likewise, when you borrow money from the bank, the bank collects interest on its loan to you.
Simple interest - a type of interest, money, paid only on the principal. Principal -the amount of money deposited or borrowed. Use the following formula to solve simple interest problems. I=Prt Rate (percent) of interest per year (as a decimal) Interest I= P · r · t Time in years that the money earns interest Principal
Teacher Example 1A: Using the Simple Interest Formula Find the missing value. I = , P =$575, r =8%, t = 3 years I =P · r · t Substitute. Use 0.08 for 8%. I =575 · 0.08 · 3 I = $138 Multiply. The simple interest is $138.00.
Together with Teacher: Example 1A Find the missing value. I = , P =$525, r =7%, t = 2 years I =P · r · t I =525 · 0.07 · 2 Substitute. Use 0.07 for 7%. I = $73.50 Multiply. The simple interest is $73.50.
6-7 Practice It! #1, 5, 7
10,200r 10,200 204 10,200 = Teacher Example1B: Using the Simple Interest Formula Find the missing value (rate). I = $204, P = $1,700, r = , t = 6 years I =P · r · t 204= 1,700 · r · 6 Substitute. 204 = 10,200r Multiply. Divide by 10,200 to isolate the variable. 0.02 = r The interest rate is 2%
6,000r 6,000 600 6000 = Together with Teacher: Example 1B Find the missing value (rate). I = $600, P = $2,000, r = , t = 3 years I =P · r · t 600= 2,000 · r · 3 Substitute. 600 = 6,000r Multiply. Divide by 6,000 to isolate the variable. 0.1 = r The interest rate is 10%.
6-7 Practice It! # 11 and 15
.12P .12 204 .12 = Teacher Example1C: Using the Simple Interest Formula Find the missing value (Principle). I = $204, P = , r =2% , t = 6 years I =P · r · t 204= P · .02 · 6 Substitute. 204 = .12P Multiply. Divide by 10,200 to isolate the variable. $1,700 = P The Principle is $1,700
0.03P 0.03 600 0.03 = Together with Teacher: Example 1B Find the missing value (Principle). I = $600, P =, r = 1% , t = 3 years I =P · r · t 600= P· .01· 3 Substitute. 600 = .03P Multiply. Divide by 6,000 to isolate the variable. $2000 = P The Principle is $2000.
6-7 Practice It! # 3 and 9
1 Understand the Problem Teacher Example 2: Problem Solving Application Avery deposits $6,000 in an account that earns 4% simple interest. How long will it take for his account balance to reach $6,800? Rewrite the question as a statement: • Find the number of years it will take for Avery’s account to reach $6,800. List the important information: •The principal is $6,000. • The interest rate is 4%. • His account balance will be $6,800.
2 Make a Plan Teacher Example 2 Continued Avery’s account balance A includes the principal plus the interest: A = P + I. Once you solve for I, you can use I = P · r · t to find the time.
3 Solve –6,000 – 6,000 800 240 240t 240 = Teacher Example 2 Continued A=Account Balance A=P + I Substitute. 6,800 = 6,000 + I Subtract to isolate the variable. 800 = I I = P · r · t 800 = 6,000 · 0.04 · t Substitute. Use 0.04 for 4%. Multiply. 800 = 240t Divide to isolate the variable. 3.33 t Round to the nearest hundredth. 1 3 It will take 3 years.
4 Teacher Example 2 Continued Look Back 1 3 After exactly 3 years, Avery’s money will have earned $800 in simple interest and his account balance will be $6,800. 1 3 = 800 I = 6,000 · 0.04 · 3 1 3 So it will take 3 years to reach $6,800.
1 Understand the Problem Together with Teacher: Example 2 Linda deposits $10,000 in an account that earns 8% simple interest. How long will it take for the total amount in her account to reach $12,000? Rewrite the question as a statement: • Find the number of years it will take for Linda’s account to reach $12,000. List the important information: •The principal is $10,000. • The interest rate is 8%. • Her account balance will be $12,000.
2 Make a Plan Together with Teacher : Example 2 Continued Linda’s account balance A includes the principal plus the interest: A = P + I. Once you solve for I, you can use I = P · r · t to find the time.
3 Solve –10,000 –10,000 2,000 800 800t 800 = Together with Teacher : Example 2 Continued A=P + I Substitute. 12,000 = 10,000 + I Subtract to isolate the variable. 2,000 = I I = P · r · t 2,000 = 10,000 · 0.08 · t Substitute. Use 0.08 for 8%. Multiply. 2,000 = 800t Divide to isolate the variable. 2.5 = t 1 2 It will take 2 years.
4 Together with Teacher : Example 2 Continued Look Back 1 2 After exactly 2 years, Linda’s money will have earned $2,000 in simple interest and her account balance will be $12,000. 1 2 = 12,000 I = 10,000 · 0.08 · 2 1 2 So it will take 2 years to reach $12,000.
6-7 Practice It! # 17, 18, 19
Lesson Quizzes Standard Lesson Quiz Lesson Quiz for Student Response Systems
Lesson Quiz Find each missing value. 1.I = 2.I = $18, P = $150, r = 3.I = $640, P = 4.I = $120, P = $600, r = 5% t = , P = $800, r = 10%, t = 3 years $240 6% , t = 2 years $2,000 , r = 4%, t = 8 years 4 years 5. Dennis deposits $6,000 in an account that earns 5.5% simple interest. How long will it take before the total amount is $8,000? A little over 6 years
Lesson Quiz for Student Response Systems • Identify the missing value. I = , P = $1000, r = 6%, t = 3 years A. $180 B. $200 C. $220 D. $250
Lesson Quiz for Student Response Systems 2. Identify the missing value. I = $12, P = $120, r = , t = 1 year A. 15% B. 10% C. 5% D. 3%
Lesson Quiz for Student Response Systems 3. Identify the missing value. I = $520, P = , r = 5%, t = 8 years A. $1600 B. $1500 C. $1300 D. $1000
Lesson Quiz for Student Response Systems 4. Identify the missing value. I = $140, P = $500, r = 7%, t = A. 4 years B. 5 years C. 6 years D. 7 years
Lesson Quiz for Student Response Systems 5. Tony deposits $5,000 in an account that earns 6.5% simple interest. How long will it take before the total amount is $7,000? A. a little over 9 years B. a little over 8 years C. a little over 7 years D. a little over 6 years