Answer
$t=42.972$ minutes
Work Step by Step
Newton's Law Of Cooling states that, If an object has an Initial temperature that is $D_0$ warmer than $T_s$, then at time $t$ the temperature $T(t)$ of the object is modeled by the function
$T(t)=T_s+D_0e^{-kt}$. where $k$ is a positive constants depends on the size and type of object.
$T(0)=190$, $k=0.0341$, $T(t)=90$, $T_s=60$, $D_0=190-60=130$.
$90=60+130e^{-0.0341t},$
$30=130e^{-0.0341t}$,
$0.231=e^{-0.0341t}$,
$\ln 0.231=-0.0341t$,
$t=42.972$ minutes
