A rock is dropped from a building that is 121 feet high. The rock s height h in feet after t seconds is given by the equation . At what time is the rock at a height of 75 feet? Round the answer to two decimal places.
A) 2.88 sec
B) 1.70 sec
C) 2.75 sec

Question

A rock is dropped from a building that is 121 feet high. The rock s height h in feet after t seconds is given by the equation  . At what time is the rock at a height of 75 feet? Round the answer to two decimal places.
A) 2.88 sec 
B) 1.70 sec 
C) 2.75 sec

Quizplus · Accepted Answer

Plug in h=75 into the equation and solve for t:
75 = 121e^(-t/8) 
e^(-t/8) = 75/121 
-t/8 = ln(75/121) 
t = -8*ln(75/121) 
t ≈ 1.70 seconds (rounded to two decimal places)

A Rock Is Dropped from a Building That Is 121