Precalculus question

Question

Find the time required for an investment of 5000 dollars to grow to 6500 dollars at an interest rate of 7.5 percent per year, compounded quarterly. 

Your answer is t=    years.

Answer 1

Using A=P(1+r/n)^nt

Solve for t

t = ln(A/P)/(nln(1+r/n))

n=4

4=0.075

A=6500

P=5000