Explanation:

$\text{Interest } = \frac{P \cdot N \cdot R}{100}$

$\text{Given : Principal " P =$6,870, " Period " N = 1 year, "Rate of Interest } R = 11.5$I = (6870 * 1 * 11.5) / 100 = 68.7 * 11.5 =$ 790.05

$\text{Amount " A = "Principal " P + "Interest } I$

:. A = P + I = 6,870 + 790.05 = \$ 7,660.05