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Chapter 4 Solutions
Precalculus: Mathematics for Calculus (Standalone Book)
- Depreciation Once a new car is driven away from the dealer, it begins to lose value. Each year, a car loses 10% of its value. This means that each year the value of a car is 90% of the previous year’s value. If a new car was purchased for $20,000, the value at the end of the first year would be $20000(0.90) and the value of the car after the end of the second year would be $20000(0.90)2. Complete the table shown below. What will be the value of the car at the end of the eighth year? Simplify the expression, to show the value in dollars.arrow_forwardAn Uncertain Investment Suppose you invested 1300 in the stock market two years ago. During the first year the value of the stock increased by 12%. During the second year, the value of the stock decreased by 12%. How much money is your investment worth at the end of the two-year period? Did you earn money or lose money? Note: The answer to the first question is not 1300arrow_forwardAllan invested $10,000 in a mutual fund. If the interest rate is 5%, how much will be in the account in 15 years by each method of compounding? compound quarterly compound monthly compound continuouslyarrow_forward
- Lending Money For a certain loan, the interest I due at the end of a loan period is given by I=Prt, where P is the principal barrowed, r is the yearly interest rate as a decimal, and t is the number of years since the money was barrowed. What interest is accrued if 3 years ago we barrowed 5000 at an interest rate of 5%?arrow_forwardIn the formula A(t)=P(1+rn)nt for compound interest the letters P, r, n, and t stand for __________, ______________, ____________, and _______________, respectively, and A(t) stands for ___________. So if 100 is invested at an interest rate of 6 compounded quarterly, then the amount after 2 years is __________.arrow_forwardFuture Value In certain savings scenarios, the value F of an investment after t years, the future value, is given by F=P1+rt. Here r is the yearly interest rate as a decimal, P is the amount of the original investment and t is the term of the investment. If we invest 1000 at an interest rate of 0.06 per year as a decimal, and if the term of the investment is 5 years, what is the future value?continuedarrow_forward
- An Amortization Table Suppose you borrow P dollars at a monthly interest rate of r as a decimal and wish to pay off the loan in t months. Then your monthly payment can be calculated using M=Pr(1+r)t(1+r)t1 dollars. Remember that for monthly compounding, you get the monthly rate by dividing the APR by 12. Suppose you borrow 3500 at a 9 APR meaning that you use r = 0.09/12 in the preceding formula and pay it back in 2 years. a. What is your monthly payment? b. Lets look ahead to the time when the loan is paid off. i. What is the total amount you paid to the bank? ii. How much of that was interest? c. The amount B that you still owe the bank after making k monthly payments can be calculated using the variables r, P, and t. The relationship is given by B=P((1+r)t(1+r)k(1+r)t1) dollars. i. How much do you still owe the bank after 1 year of payments? ii. An amortization table is a table that shows how much you still owe the bank after each payment. Make an amortization table for this loan.arrow_forwardCompound Interest Use the formula A=P1+rnnt to calculate the balance A of an investment when P=$3000, r=6 and t=10years, and compounding is done (a) by the day, (b) by the hour, (c) by the minute, and (d) by the second. Does increasing the number of compoundings per year result in unlimited growth of the balance? Explain.arrow_forwardThe function f(x)=5x is an exponential function with base______; f(2) =_______, f(0) =______, f(2) =_______, and f(6) =_______.arrow_forward
- Depreciation A tool and die company buys a machine for $175,000 and it depreciates at a rate of 30 per year. (In other words, at the end of each year the depreciated value is 70 of what it was at the beginning of the year.) Find the depreciated value of the machine after 5 full years.arrow_forwardThe Rule of 72 This is a continuation of Exercise 14. Financial advisors sometimes use a rule of thumb known as Rule of 72 to get a rough estimate of the time it takes for an investment to double in value. For an investment that is compounded yearly at an interest rate of r%, this rule says it will take about 72/r years for the investment to double. In this calculation, r is the integer interest rate rather than a decimal. Thus, if the interest rate is 8%, we would use 72/8 rather than 72/0.08. For the remainder of this exercise, we will consider an investment that is compounded yearly at an interest rate of 13%. a. According to the Rule 72, how long will it take the investment to double in value? Parts b and c of this exercise will check to see how accurate this estimate is for this particular case. b. Using the answer you got from part a of this exercise, calculate the future value interest factor as defined in Exercise 14. Is it exactly the same as your answer to the part a of Exercise 14? c. If your initial investment was 5000, use your answer from part b to calculate the future value. Did your investment exactly double? Future Value Business and finance texts refer to the value of an investment at a future time as its future value. If an investment of P dollars is compounded yearly at an interest rate of r as a decimal, then the value of the investment after t years is given by FutureValue=P1+rt. In this formula, 1+rt is known as the future value interest factor, so the formula above can be written as FutureValue=PFuturevalueinterestfactor Financial officers normally calculate this or look it up in a table a. What future value interest factor will make an investment double? b. Say you have an investment that is compounded yearly at a rate of 9%. Find the future value interest factor for a 7-year investment. c. Use the results from part b to calculate the 7-year future value if your initial investment is 5000.arrow_forward
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