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Problem of the day. When making a purchase for a big ticket item (house, car, etc.) in the near future, you might want to talk to friends and associates about the purchase to seek their:. Lesson Objective Determine the compound interest and the amount. Content Vocabulary. compound interest.
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Problem of the day.. • When making a purchase for a big ticket item (house, car, etc.) in the near future, you might want to talk to friends and associates about the purchase to seek their:
Lesson Objective Determine the compound interest and the amount. Content Vocabulary • compound interest compound interest Interest earned not only on the original principal but also on the interest earned during previous interest periods, earning interest on interest.
Remember “Time Value of Money” • The longer you keep money in an interest bearing account, the more money you will make • Compounding can be done different ways, and the more frequently interest compounds, the faster it grows. • See example on the next slide:
Calculated for an 18 year old person investing at 8% until age 65.
“Compound Interest is the most powerful force in the universe”
Quarterly: A period of time out of one year. Each year has 4 quarters. One quarter is how many months? 3 months
Example:You open a savings account and deposit $1,000. Your bank advertises a 6% annual interest rate that is compounded quarterly (that means you calculate interest every 3 months and add it to the principal). What is the amount in the account at the end of one year? How much is the compound interest? 1. Find the interest at the end of the 1st quarter by using I = P x R x T $______ x _____ x _____ = $________ 2. Find the Amount at the end of the 1st quarter (A = P + I) $________ + $________ = $_________
3. Find the interest at the end of the 2nd quarter using the “new” Principal. $_________ x _________ x ________ = ______ 4. Find the Amount at the end of the 2nd quarter $______ + $_______= $_________
5. Find the interest at the end of the 3rd quarter using the “new” Principal. $________ x _______ x _________ = ___________ (round) = ___________(interest) 6. Find the Amount at the end of the 3rd quarter $_________ + $_______ = $___________
7. Find the interest at the end of the 4th quarter using the “new” Principal. $________ x _____ x ______= $_______ round $________ 8. Find the Amount at the end of the 3rd quarter $__________ + $________ = $____________ This is how much money is in the bank at the end of the year
How much total interest did you earn? • $15.00 (1st quarter) + $15.23 (2nd quarter) + $15.45 (3rd quarter) + $15.69 (4th quarter) = $61.37
Assignment: p. 227 (9, 11, 12, 14, 21) *semiannually = 2 times a year
Challenge Problem: $10,000 investment earned interest at 4.5% compounded quarterly for 1 year and 5.5% compounded quarterly for the next year. What is the amount in the account at the end of 2 years? How many different compounding periods are there? ____ Setup of the first year: Setup of the second year:
Challenge: Hint • 8 periods • 10,000 x .045 x ¼ , calculate four times add interest to principal after each period • 10,000 x .055 x ¼ , calculate four times add interest to principal after each period
Answer: 11,044.80
www.marsbank.com savings calculator
p. 227 Answer keys $1,200 x .06 x 3/12 = $18 $1,200 + $18 = $1,218 $1,218 x .06 x 3/12 = $18.27 $1,218 + $18.27 = $1236.27 (a.) $18 + $18.27 = $36.27 (b.) 12. $860 x .055 x 6/12 = $23.65 $860 + $23.65 = $883.65 $883.65 x .055 x 6/12 = $24.30 $883.65 + $24.30 = $907.95 (a.) $23.65 + $24.30 = $47.95 (b.)
$9,544 x .0525 x 1/12 = $41.755 ($41.76) $9,544 + $41.76 = $9,585.76 $9,585.76 x .0525 x 1/12 = $41.94 $9,585.76 + $41.94 = $9,627.70 $9,627.70 x .0525 x 1/12 = $42.12 $9,627.70 + $42.12 = $9669.82 $9669.82 x .0525 x 1/12 = $42.31 $9669.82 + $42.31 = $9,712.13 (a.) $41.76 + $41.94 + $42.12 + $42.31 = $168.13
$875 x .04 x 3/12 = $8.75 $875 + $8.75 = $883.75
#16– Page 227 2000 dollars @ 6% compounded semiannually ( 2x) I= P x R x T July 1st - I= 2000 x .06 x 6/12 = 60 A = I + P A = 60 + 2000 = 2060 Add: 2000 dollars January 1 – I = (2060 + 2000) x .06 x 6/12 = 4060 x .06 x 6/12 = 121.80 Amount = 4060 + 121.80 = 4181.80 Finally, compound interest = 181.80