Question 75481
let x equal the certain sum...she invested x at 9%, 2x at 10%, and 3x at 11%...so the total interest would be (x*.09)+(2x*.10)+(3x*.11)


this means that .62x=310...so x=500


Sally invested $500 at 9%, $1000 at 10%, and $1500 at 11%