<h2>Explanation:</h2><h2></h2>
Here we know that Margie is standing on a bridge looking at the river. She throws a rock over the bridge with an initial velocity of 60 ft/sec. The height, h, of the rock at the rime t seconds after it was thrown can be modeled by the equation:
To calculate how long will it take for the rock to reach the surface of the water, we need to set . So:
Given that time can't be negative, we just choose the positive value. Therefore, <em>it will take 4.70 seconds for the rock to reach the surface water.</em>