4.7.2: Practice with Compound Interest

Finite Math (SJDC M20) v2 · LibreTexts

0%

Contents

    Text

    Size
    100%
    Theme
    Typeface
    Line length
    Spacing

    From LibreTexts, under CC BY 4.0, as the source states it; its equations are written in TeX, which the PDF shows typeset. This page at LibreTexts.

    PROBLEM SET: COMPOUND INTEREST

    Do the following compound interest problems involving a lump-sum amount.

    1) What will the final amount be in 4 years if $8,000 is invested at 9.2% compounded monthly.?

    2) How much should be invested at 10.3% for it
    to amount to $10,000 in 6 years?

    3) Lydia's aunt Rose left her $5,000. Lydia spent $1,000 on her wardrobe and deposited the rest
    in an account that pays 6.9% compounded daily. How much money will she have in 5 years?

    		 4) Thuy needs $1,850 in eight months for her college tuition. How much money should she deposit lump sum in an account paying 8.2% compounded monthly to achieve that goal?

    5) Bank A pays 5% compounded daily, while
    Bank B pays 5.12% compounded monthly. Which bank pays more? Explain.

    		 6) EZ Photo Company needs five copying machines in 2 1/2 years for a total cost of $15,000. How much money should be deposited now to pay for these machines, if the interest rate is 8% compounded semiannually?
    7) Jon's grandfather was planning to give him $12,000 in 10 years. Jon has convinced his grandfather to pay him $6,000 now, instead. If Jon invests this $6,000 at 7.5% compounded continuously, how much money will he have in 10 years? 8) What will be the price of a $20,000 car in 5 years if the inflation rate is 6%?

    PROBLEM SET: COMPOUND INTEREST

    Do the following compound interest problems.

    9) At an interest rate of 8% compounded continuously, how many years will it take to double your money? 10) If an investment earns 10% compounded continuously, in how many years will it triple? .
    11) The City Library ordered a new computer system costing $158,000; it will be delivered in 6 months, and the full amount will be due 30 days after delivery. How much must be deposited today into an account paying 7.5% compounded monthly to have $158,000 in 7 months? 12) Mr. and Mrs. Tran are expecting a baby girl in a few days. They want to put away money for her college education now. How much money should they deposit in an account paying 10.2% so they will have $100,000 in 18 years to pay for their daughter's educational expenses?
    13) Find the effective interest rate for an account paying 7.2% compounded quarterly. 14) If a bank pays 5.75% compounded monthly, what is the effective interest rate?

    15) The population of the African nation of Cameroon was 12 million people in the year 2015; it has been growing at the rate of 2.5% per year. If the population continues to grow that rate,what will the population be in 2030?
    (http://databank.worldbank.org/data on 4/26/2016)

    		 16) According to the Law of 70, if an amount grows at an annual rate of 1%, then it doubles every seventy years. Suppose a bank pays 5% interest, how long will it take for you to double your money? How about at 15%?

    This page titled 4.7.2: Practice with Compound Interest was last modified on Sat, 01 Aug 2026 17:55:28 GMT and is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Rupinder Sekhon and Roberta Bloom via source content that was edited to the style and standards of the LibreTexts platform.