Do Now 4/12/11Do Now 4/12/11 Take out HW from last night.Take out HW from last night.

Text p. 365, #8-16 evens and #15Text p. 365, #8-16 evens and #15

Copy HW in your planner.Copy HW in your planner. Text p. 365, #18, 20, 23, 26Text p. 365, #18, 20, 23, 26 Text p. 809, #25-36 allText p. 809, #25-36 all Quiz sections 7.5-7.7 Wednesday (Bring notecard for quiz)Quiz sections 7.5-7.7 Wednesday (Bring notecard for quiz) Chapter 7 Test FridayChapter 7 Test Friday

In your notebook, answer the following question. Find the In your notebook, answer the following question. Find the simple interest on an account with the following: interest simple interest on an account with the following: interest rate = 7%, principal = $325, time = 8 years. What is the rate = 7%, principal = $325, time = 8 years. What is the account balance after the 8account balance after the 8thth year? year?

Interest = (325)(0.07)(8)Interest = (325)(0.07)(8) = $182.00= $182.00

Balance = Principal + Balance = Principal + InterestInterest

= $325 + $182.00= $325 + $182.00= $507.00= $507.00

HomeworkHomework Text p. 365, #8-16 evens & 15 Text p. 365, #8-16 evens & 15

8) $500; $17508) $500; $1750 10) $72.90; $672.9010) $72.90; $672.90 12) $4; $10412) $4; $104 14) $30614) $306 16) 6.25%16) 6.25%

15) 15) BalanceBalance PrincipalPrincipal Interest RateInterest Rate TimeTime

$5,000$5,000 $4,000$4,000 5%5% 5 years5 years

$11,160$11,160 $9,000$9,000 8%8% 36 months36 months

$3,207$3,207 $3,000$3,000 4.6%4.6% 18 months18 months

Objective

SWBAT calculate interest earned and account balances

SWBAT review percent of change, percent applications, and simple and compound interest

Is the product of the principal, the annual

interest rate, and the time in years.

Principal Principal – the amount borrowed, loaned, or in savings.– the amount borrowed, loaned, or in savings.

Annual interest rateAnnual interest rate – the percent of the principal you would – the percent of the principal you would earn (or pay) as interest in ONE year.earn (or pay) as interest in ONE year.

trPI

Time in yearsTime in years – when time is less than a year, write time as a – when time is less than a year, write time as a fraction of the year. fraction of the year.

Section 7.7 “Simple and Compound Interest”

SIMPLE INTEREST-

Writing Time in Years…

4

1

12

3

12

7

trPI Time in yearsTime in years – when time is less than a year, write time as a – when time is less than a year, write time as a fraction of the year. fraction of the year.

Write the months as a fraction of a year.

3 months

6

5

12

10

7 months 10 months

Simple Interest

You have $1,000 in a savings account in a local bank. The annual interest rate is 3%. How much interest will the bank pay you in a month?

12

103.01000 I

50.2$I

Principal = $1000Principal = $1000

Interest rate = 3% or 0.03Interest rate = 3% or 0.03

Time = one month or 1/12Time = one month or 1/12

trPI

Simple Interest

You borrowed $18,000 for a new car. The annual interest rate is 12%. What is the interest you will have to pay in two years to borrow this money?

212.018000 I

4320$I

Principal = $18,000Principal = $18,000

Interest rate = 12% or 0.12Interest rate = 12% or 0.12

Time = two years or 2Time = two years or 2

trPI

Account Balance

When an account earns interest it is added to the money in the account. The BALANCE (A) of an account that earns simple annual interest is the sum of the principal (P) and the interest (Prt).

tPA PrBalance

Finding an Interest Rate

Suppose you save $1400 in a savings account that earns simple annual interest. After 9 months, the balance in your account is $1421. Find the annual interest rate.

Principal = $1400Principal = $1400

Balance = $1421Balance = $1421

Time = 9 monthsTime = 9 monthsr)4/3(140014001421

r105021

tPA Pr

r02.0 The interest The interest rate is 2%rate is 2%

This makes more “cents”…

COMPOUND INTEREST-Is interest that is earned on BOTH the principal and any interest that has been earned previously.

Principal Principal – the amount borrowed, loaned, or in savings.– the amount borrowed, loaned, or in savings.

Annual interest rateAnnual interest rate – the percent of the principal you would – the percent of the principal you would earn (or pay) as interest in ONE year.earn (or pay) as interest in ONE year.

trPA )1(

Time in yearsTime in years – when time is less than a year, write time as a – when time is less than a year, write time as a fraction of the year. fraction of the year.

Account balanceAccount balance– the amount of money in an account.– the amount of money in an account.

You deposit $300 in the bank. This is your beginning balance. The annual interest rate is 6%. Each year the simple interest is computed and then added to your beginning balance. (this is compounded interest). If this pattern continues, how much will you have in the account at the end of 3 years?

3)06.01(300 A

30.357$A

Principal = $300Principal = $300

Interest rate = 6% Interest rate = 6%

Time = 3 yearsTime = 3 years

trPA )1(

After 3 years you will have $357.30 After 3 years you will have $357.30

This makes more “cents”…

Compound Interest

You deposit $1,500 in a savings account in a local bank. The annual interest rate is 2.4% compounded annually. Find the balance after 6 years?

Principal = $1500Principal = $1500

Interest rate = 2.4% or 0.024Interest rate = 2.4% or 0.024

Time = 6Time = 6

6)024.01(1500 A

38.1729$A

trPA )1(

Quiz sections 7.5-7.7 ReviewQuiz sections 7.5-7.7 Review

The percent of change of a quantity is given by:

The percent is a PERCENT of INCREASE if the quantity increased and it is a PERCENT of DECREASE if the quantity decreased.

Amount of Amount of changechange

Original amountOriginal amount

Section 7.5 “Percent of Change”

Percent of change indicates how much a quantity increases or decreases with respect to the original amount.

Section 7.6 “Percent Applications”

Percents can be applied to many Percents can be applied to many everyday ordinary activities: everyday ordinary activities:

1) markups1) markups

2) discounts2) discounts

3) sales tax3) sales tax

4) tips4) tips

MarkupsRetail priceRetail price == Wholesale priceWholesale price + + MarkupMarkup

(% of wholesale price)(% of wholesale price)

DiscountsSale priceSale price == Original priceOriginal price – – DiscountDiscount

(% of original (% of original price)price)

Sales Tax and TipsTotal costTotal cost == Food billFood bill + + Sales taxSales tax

(% of bill)(% of bill) + + TipTip

(% of (% of bill)bill)

Is the product of the principal, the annual interest

rate, and the time in years.

Principal Principal – the amount borrowed, loaned, or in savings.– the amount borrowed, loaned, or in savings.

Annual interest rateAnnual interest rate – the percent of the principal you would – the percent of the principal you would earn (or pay) as interest in ONE year.earn (or pay) as interest in ONE year.

trPI

Time in yearsTime in years – when time is less than a year, write time as a – when time is less than a year, write time as a fraction of the year. fraction of the year.

Section 7.7 “Simple and Compound Interest”

SIMPLE INTEREST-

Finding an Interest Rate…

When an account earns interest it is added to the money in the account. The BALANCE (A) of an account that earns simple annual interest is the sum of the principal (P) and the interest (Prt).

tPA PrBalance

This makes more “cents”…

COMPOUND INTEREST-Is interest that is earned on BOTH the principal and any interest that has been earned previously.

Principal Principal – the amount borrowed, loaned, or in savings.– the amount borrowed, loaned, or in savings.

Annual interest rateAnnual interest rate – the percent of the principal you would – the percent of the principal you would earn (or pay) as interest in ONE year.earn (or pay) as interest in ONE year.

trPA )1(

Time in yearsTime in years – when time is less than a year, write time as a – when time is less than a year, write time as a fraction of the year. fraction of the year.

Account balanceAccount balance– the amount of money in an account.– the amount of money in an account.

Notecard On one side of your notecard, you may write in the formulas for percent

of change, percent applications, and simple and compound interest.

prtpA

trPA )1( prtI Simple Interest Compound Interest

100||

original

changeofamountP

Percent of Change

Markup

Retail priceRetail price == Wholesale priceWholesale price + + MarkupMarkup(% of wholesale price)(% of wholesale price)Discount

Sale priceSale price == Original priceOriginal price – – DiscountDiscount(% of original price)(% of original price)

Sales Tax & Tip

Total priceTotal price == Original priceOriginal price + + Sales TaxSales Tax(% of original price)(% of original price)

+ + TipTip(% of original price)(% of original price)

Classwork Text p. 365, #18, 20, 23, 26Text p. 365, #18, 20, 23, 26