Given:
initial investment: $250
term: 2 years
interest earned: $7.50
Because it was stated that $7.50 is the simple interest, we will use this formula:
Interest = Principal * Interest Rate * Term
7.50 = 250 * Interest Rate * 2
7.50 = 500 * Interest Rate
7.50 / 500 = Interest Rate
0.015 or 1.5% = Interest Rate
The interest rate for the initial investment of $250 for 2 years is 1.5%. Thus, it earned a simple interest of $7.50