You deposit $1,000 in a fund earning 5.75%. How long will it take to double your money? Solution Let us suppose that it will take n years to get double. Hence, 1000(1+0.0575)^n=2000 or,log1000+nlog(1.0575)=log2000 or, 3+0.024280n=3.30102 or, n=0.301029/0.024280=12.3 Hence it will take almost 12.3years to get double.