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Applied Calculus (MAT 121) Dr. Day Thur sday March 8, 2012. Continuously Compounded Interest (5.3) Continuous Compounding compared to Periodic Compounding Solving Problems: What’s the Unknown?. Exponential Functions. Big Ideas What are Exponential Growth and Exponential Decay?
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Applied Calculus (MAT 121)Dr. DayThursday March 8, 2012 • Continuously Compounded Interest (5.3) • Continuous Compounding compared to Periodic Compounding • Solving Problems: What’s the Unknown? MAT 121
Exponential Functions Big Ideas • What are Exponential Growth and Exponential Decay? • What sort of applications use exponential functions as their mathematical models? • What algebra do we need to remember to work with exponential functions? • How do we undo exponentiation? We need the inverse function, called the logarithm function. • Where does calculus fit in to all of this? MAT 121
Using Logarithms to Solve Equations • Halley's law states that the barometric pressure (in inches of mercury) at an altitude of x mi above sea level is modeled by the function p(x) = 29.92e-0.2x (x≥ 0) If the barometric pressure as measured by a hot-air balloonist is 23.2 in. of mercury, what is the balloonist's altitude? Round your answer to two decimal places. MAT 121
Compound Interest Periodic Compounding • A: amount in account • P: amount of original deposit (principal) • i: annual interest rate, expresses as a decimal value • n: number of compounding periods per year • t: number of years the principal remains in account Continuous Compounding • A: amount in account • P: amount of original deposit (principal) • r: annual interest rate, expresses as a decimal value • t: number of years the principal remains in account MAT 121
Compound Interest Suppose $2500 is deposited in a savings account earning 1.25% annual interest compounded annually. Assuming no deposits or withdrawals, what will be the value of the account in 8 years? What if the same the account used continuously compounded interest? MAT 121
Compound Interest Assume continuous compounding for the following problems. • Calculate the amount accumulated after 3 years if $7800 is invested at 9% per year. How much of that is interest? • Calculate the interest rate needed for an investment of $8,000 to grow to $10,000 in 10 years. Round to the nearest hundredth of a percentage point. • How long will it take for an investment of $7,000 to double if the investment earns interest at the rate of 3% per year? • Calculate the principal required in order to create an account with a value of $25000 after 3 years at an interest rate of 12% per year. MAT 121
Assignments WebAssign 5.3 due tomorrow 5.4 due Monday 3/19 Reminder: Check results for Test #3 Look at the multiple-choice correction sheet. Review the written comments I added to your test. Study the solution guide available on course website. MAT 121