P=present value of investment = 2800 i=interest per quarter=0.07/4=0.0175 n=number of quarters money invested (to be calculated) Interest = P[(1+i)^n-1]=500 2800((1+0.0175)^n-1)=500 (1+0.0175)^n=500/2800+1 take log on both sides n(log(1.0175)=log(1+500/2800) n=log(1+500/2800)/log(1.0175) =9.471 quarters =37.88 months =37.9 months [ nearest tenth of a month ]
