Your question is not basically about portfolio management. Portfolio management will generally involve Beta factor, standard deviation, risk free rate....so on. Even I don't think this question can be classified as business math. This question basically involves the use of the compound interest rate formula. But if you insist to call this a business math question , then the concept you are talking about is FV i.e future value of annuity. The first amount 100(assuming it is a scrip) bears an interest rate of 8%, the second scrip 200 bears an interest rate of 7% and the third scrip 300 bears an interest rate of 1%. There is no further information-whether the interest rates are annual or monthly etc. Nevertheless assuming x as one time period you can easily calculate the cash flow for each scrip separately and then check by adding the compound value of the three scrips where the sum equals or exceeds 2000. You can use calculator or FVIF (future value interest factor for annuity) Table for speedy calculations.