The quadratic function h(t) = -16.1t2 + 150 models a ball's height, in feet, over time, in seconds,
after it is dropped from a 15 story building.
from what height, in feet, was the ball dropped?
after how many seconds, rounded to the nearest hundredth, did the ball hit the ground?

ANSWER

a) 150ft

b) 3.05s

EXPLANATION.

The quadratic function that models the height of the ball is

The ball was dropped at time t=0.

We plug in t=0 into the given function to get,

Therefore the ball was dropped from a height of 150 ft.

When the ball hit the ground, then h(t)=0.

This implies that:

We take square root of both sides,

to the nearest hundredth.

Therefore the ball hit the ground after approximately 3.05 seconds.

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