A ball is thrown from a roof. Its height in feet is described by the equation t seconds after launch. When is the ball at a height of 64 feet?

Question

A ball is thrown from a roof. Its height in feet is described by the equation  t seconds after launch. When is the ball at a height of 64 feet?

Quizplus · Accepted Answer

We need to solve the equation 11ec19db_8527_9a93_9dbe_d1c5bebef213_TBX8673_11t = 64 for t. 
Substituting the known values, we get: 
11ec19db_8527_9a93_9dbe_d1c5bebef213_TBX8673_11t = 64 
11ec19db_8527_9a93_9dbe_d1c5bebef213_TBX8673_11t = 2^6 
Taking the logarithm of both sides, we get: 
t = log(2^6)/11ec19db_8527_9a93_9dbe_d1c5bebef213_TBX8673_11 
t = 6*log(2)/11ec19db_8527_9a93_9dbe_d1c5bebef213_TBX8673_11 
t ≈ 2.079 seconds (rounded to three decimal places) 
Therefore, the ball is at a height of 64 feet approximately 2.079 seconds after launch, which is closest to choice B, 3 seconds.

A Ball Is Thrown from a Roof