During a bounce on a trampoline, the height (h feet) of a child above the ground is related to time (t seconds) by a quadratic function of the form h = -4.9t2 + 7t + 3. The maximum height of the child above the ground, to the nearest tenth of a foot, is
h is a max at the vertex, which is always at t = -b/2a, which is 7/9.8 = 0.7143 in this problem
So you just want h(0.7143)