start by converting the number of months into years
[tex]3months\cdot\frac{1\text{year}}{12\text{months}}=\frac{1}{4}\text{years}=0.25\text{years}[/tex]continue by applying the simple interest formula
[tex]I=p\cdot r\cdot t[/tex]in which p is the principal, r is the rate and t is the time in years
[tex]\begin{gathered} I=10000\cdot0.04\cdot0.25 \\ I=100 \end{gathered}[/tex]The simple interest is $100