Okay, here we have this:
Considering the provided information, we are going to calculate the requested time, so we obtain the following:
[tex]h(t)=-16t^2+10[/tex]And he caught them at a height of 4 feet, so we'll substitute and solve for t:
[tex]4=-16t^2+10[/tex]Solving:
[tex]\begin{gathered} 4=-16t^2+10 \\ -16t^2+10-10=4-10 \\ -16t^2=-6 \\ \frac{-16t^2}{-16}=\frac{-6}{-16} \\ t^2=\frac{3}{8} \\ t=\sqrt{\frac{3}{8}} \\ t\approx0.61 \end{gathered}[/tex]Finally we obtain that the time where approximately 0.61.