The angular position of a rotating object as a function of time is given below:

$(t)=4t^3+1t^2-5t+1$

Here $$ is in units of radians and $t$ is in units of seconds. Determine the average angular acceleration of the object between $t=1s$ and $t=3s.$ Express your answer using zero decimal places in units of $ra\frac{d}{s^2}.$