Answer :
The height of the ball at time t is modeled by
[tex]H(t)=3+29t-16t^2[/tex]To find the values of t for which the height is 15 feet, let us solve the equation
[tex]\begin{gathered} H(t)=15 \\ 3+29t-16t^2=15 \\ 16t^2-29t+12=0 \\ x=\frac{29\pm\sqrt[]{73}}{32} \\ =0.64,1.17 \end{gathered}[/tex]So, at t=0.6 sec and =1.173 sec, the height of the ball is 15 feet (Rounding off to the nearest hundredth)