Your work is correct. The only thing you could have done differently would be to get the investments to the nearest penny instead of the nearest dollar. Then the interest on the $3333.33 would be $166.66 (interest is always rounded down, for doing that benefits the interest-giver and not the investor. And over a long period of time with many investors those small fractions of a cent amount to many thousands of dollars!) The interest on the $6666.67 would be $466.66 and the total interest would be $633.32. I'm not sure that's really "better". If so, it isn't much "better", as 32 cents isn't worth very much these days! :-) Edwin