4. Joe deposits $2,000 into a savings account. The account compounds his money quarterly at a rate of 4%. a) How much money does Joe have after a year? Round your answer to the nearest ten cents. b) After 18 months? Round your answer to the nearest dollar. c) When will his account grow to $25,000? Round your answer to the nearest year.

Respuesta :

Answer:

Step-by-step explanation:

Formula to be used,

Final amount = [tex]\text{Initial amount}\times(1+\frac{r}{n})^{nt}[/tex]

r = rate of interest

n = number of compounding in a year

t = Duration of investment in years

Initial amount = $2000

r = 4% = 0.04

n = 4

A). Final amount = [tex]2000(1+\frac{0.04}{4})^{4\times 1}[/tex]

                           = 2000(1.01)⁴

                           = 2081.21

                           ≈ $2081

B). If t = 18 months ≈ 1.5 years

    Final amount = [tex]2000(1.01)^{4\times 1.5}[/tex]

                           = [tex]2000(1.01)^6[/tex]

                           = 2123.04

                           ≈ $2123

C). If final amount = $25000

     25000 = [tex]2000(1.01)^{4\times t}[/tex]

     [tex]\frac{25}{2}=(1.01)^{4t}[/tex]

     12.5 = [tex](1.040604)^t[/tex]

     log(12.5) = [tex]\text{log}(1.040604)^t[/tex]

     log(12.5) = t[log(1.040604)]

     t = [tex]\frac{\text{log}(12.5)}{\text{log}(1.040604)}[/tex]

       = 63.458

       ≈ 64 years