Question 387646
h(t)=-9.8t^2-10t+190
Set h(t) to zero and solve for t:
0=-9.8t^2-10t+190
0=-4.9t^2-5t+95
since we can't factor, we apply the quadratic formula.  Doing so yields:
t = {-4.94, 3.92}
Tossing out the negative solution leaves us with:
t = 3.92 seconds
.
Details of quadratic follows:
*[invoke quadratic "t", -4.9, -5, 95 ]