Simple-interest maturity value of a deposit

Statement

Mr Melloni deposits $2500\ \text{€}$ in an account paying $3\%$ per year of simple interest. How much will he have after $4$ years? How much interest accrues?

Solution

The simple-interest maturity value is $M=C\,(1+r\,t)$. $M=2500\,(1+0{.}03\cdot 4)=2500\cdot 1{.}12=\boxed{2800\ \text{€}}.$ Interest: $I=M-C=2800-2500=\boxed{300\ \text{€}}$.