Get Full Access to Grade 10 Mathematics PT and CAT Master Course (Entered in Quill)
Currently, you have limited access to Grade 10 Mathematics PT and CAT Master Course (Entered in Quill). The Full Program includes,
Buy Practice Resources
Online ProgramThe amount of money A in an investment after t years with a principal amount P that has a rate of interest of r compounded n times a year is given by,
\(A(t)=P\left(1+\frac{r}{n} \right)^{nt} .\)
Annette want to find the time it will take for an initial investment of $3,000 at 7% interest compounded quarterly to accumulate to $6,500. When she plugs her values into the formula, she get
\(6,500=3,000\left(1+\frac{.7}{4} \right)^{4t} \)
\(\frac{6,500}{3,000} =\left(1+\frac{.7}{4} \right)^{4t}\)
\(\frac{6,500}{3,000} =\left(1.175\right)^{4t} \)
\(\ln \left(\frac{6,500}{3,000} \right)=\ln \left(1.175\right)^{4t} \)
\(\ln \left(\frac{6,500}{3,000} \right)=4t\ln \left(1.175\right)\)
\(\frac{\ln \left(\frac{6,500}{3,000} \right)}{\ln \left(1.175\right)} =4t\)
\(4\left(\frac{\ln \left(\frac{6,500}{3,000} \right)}{\ln \left(1.175\right)} \right)=t\)
4.8=t
The correct answer should be 11.1 years. Explain what went wrong in steps 1-8 in Annette's calculations.