double the rate The amount of money in an account after simple interest has been earned is given by the formula: A = Principal + Interest Earned or A = P + P* R * T Choose your principal and time and solve for the rate. The given values are P = $1000 T = 2 A = $1080 Now apply the vlues on the formula R to find the value of it, => R = ([1080/1000]-1/2 => R = (1.08 -1)/2 => R = 0.08/2 => R = 0.04