Do Now 4/23/10Do Now 4/23/10 Take out HW from last night.Take out HW from last night.

Practice worksheet 7.6 oddsPractice worksheet 7.6 odds

Copy HW in your planner.Copy HW in your planner. Text p. 365, #8-16 evens and #15Text p. 365, #8-16 evens and #15

In your journal, answer the following In your journal, answer the following question. A shoe store in NJ has a sale on question. A shoe store in NJ has a sale on sneakers for 15% off. If the original price sneakers for 15% off. If the original price is$75 what is the total cost of the sneakers is$75 what is the total cost of the sneakers with tax? with tax?

A shoe store in NJ has a sale on A shoe store in NJ has a sale on sneakers for 15% off. If the original price sneakers for 15% off. If the original price is$75 what is the total cost of the is$75 what is the total cost of the sneakers with tax? sneakers with tax?

Sale priceSale price == Original priceOriginal price – – DiscountDiscount

== – – (15(15% · 75)% · 75)

== 7575 – – 11.2511.25

==

7575

$63.75$63.75

Total PriceTotal Price == Purchase PricePurchase Price + + Sales TaxSales Tax

$63.75$63.75 + + (63.75 x 7%)(63.75 x 7%)

$63.75$63.75 + + 4.464.46

$68.21$68.21

HomeworkHomework Practice worksheet 7.6 Practice worksheet 7.6

oddsodds 1) $11.251) $11.25 3) $2733) $273 5) $49.405) $49.40 7) $30.607) $30.60 9) $29.269) $29.26 11) $86.5111) $86.51

13) $83.6413) $83.64 15) $36.1515) $36.15 17) $19.3817) $19.38 19) $27.0419) $27.04 21) $57.4021) $57.40

ObjectiveObjective SWBAT calculate interest earned and SWBAT calculate interest earned and

account balancesaccount balances

Is the product of the Is the product of the principalprincipal, the , the

annual interest rateannual interest rate, and the , and the time in yearstime 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 Section 7.7 “Simple and Compound Interest”Interest”

SIMPLE INTEREST-SIMPLE INTEREST-

Writing Time in Years…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 InterestSimple Interest You have $1,000 in a savings account You have $1,000 in a savings account

in a local bank. The annual interest rate in a local bank. The annual interest rate is 3%. How much interest will the bank is 3%. How much interest will the bank pay you in a month? 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

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Simple InterestSimple Interest You borrowed $18,000 for a new car. You borrowed $18,000 for a new car.

The annual interest rate is 12%. What is The annual interest rate is 12%. What is the interest you will have to pay in two the interest you will have to pay in two years to borrow this money? 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

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Account BalanceAccount Balance

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

tPA PrBalance

Finding an Interest Finding an Interest RateRate

Suppose you save $1400 in a savings Suppose you save $1400 in a savings account that earns simple annual account that earns simple annual interest. After 9 months, the balance in interest. After 9 months, the balance in your account is $1421. Find the annual your account is $1421. Find the annual interest rate. 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”…This makes more “cents”…

COMPOUND INTEREST-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.

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

3)06.01(300 A

30.357$A

Principal = $300Principal = $300

Interest rate = 6% Interest rate = 6%

Time = 3 yearsTime = 3 years

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

This makes more “cents”…This makes more “cents”…

Compound InterestCompound Interest You deposit $1,500 in a savings You deposit $1,500 in a savings

account in a local bank. The annual account in a local bank. The annual interest rate is 2.4% compounded interest rate is 2.4% compounded annually. Find the balance after 6 annually. Find the balance after 6 years? 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

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HomeworkHomework Text p. 365, #8-26 evensText p. 365, #8-26 evens

2424

Word ProblemWord Problem You deposit $300 in the bank. This is your You deposit $300 in the bank. This is your

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

106.0300 I18$I

Principal = $300Principal = $300

Interest rate = 6% Interest rate = 6%

Time = one yearTime = one year

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YEAR 1YEAR 1

106.0318 I

08.19$I

Principal = $318Principal = $318

Interest rate = 6%Interest rate = 6%

Time = one yearTime = one year

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YEAR 2YEAR 2

106.008.337 I22.20$I

Principal = $337.08Principal = $337.08

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

Time = one yearTime = one year

trPI

YEAR 3YEAR 3

Interest rate = 6%Interest rate = 6%