Top bond fund. An investment of $10,000 in 1997 in the Spartan Investment Grade Bond Fund grew to $14,309.61 in 2002 (
www.fidelity.com). Use the formula:r = (s/p)^(1/n) - 1to find the 5-year average annual return.p is the initial investment.s is the amount it is worth after n years.r is the rate of return.