Answer:
about 151 feet
Step-by-step explanation:
The height of the ball at a time of 3.1 seconds is given by Charlize's equation as ...
h(3.1) = -16(3.1)^2 +3 = -150.76 . . . feet
The well is about 151 feet deep.
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Comment on this measurement
The speed of sound is sufficiently slow that it will make a difference in the time Charlize records. She would get a more accurate measurement if she were able to see the ball hit bottom.