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1) How long would it take an investment to double under each of the following co

ID: 3342899 • Letter: 1

Question

1) How long would it take an investment to double under each of the following conditions? (a) Interest is 3.2% compounded monthly. (Round your answer to three decimal places.) (b) Interest is 5% compounded continuously. (Round your answer to three decimal places.) 2) How much money would you have to invest today at 6% APR compounded monthly to accumulate the sum of $150,000 in 25 years? (Round your answer to two decimal places.) 3) In March 2009, the Bill and Melinda Gates Foundation granted $76 million to AED to fund the Alive and Thrive Initiative. In 2009, Bill Gates, the cofounder and former CEO of Microsoft, had an estimated net worth of $56 billion. How long does it take $56 billion invested at an effective rate of 6.1% to earn $76 million? (Round your numerical answer to four decimal places.)

Explanation / Answer

1

a) 2 = 1 * ( 1 + 0.032 / 12 ) ^x

so taking log on both sides..


x ln ( 1 + 0.032/12 ) = ln 2

x = 260.277 months = 21.690 years


b)

2 = e^(0.05 * t )

so t = 13.863 years




2)

150000 = P * [ 1 + ( 0.06 / 12 ) ] ^ (25* 12)


so P = $ 33,594.85


3) 76 = 56 * ( 1 + 0.061)^n

taking log on both sides


n * ln ( 1.061) = ln( 76/56)


so number of years = n = 5.15744 years