The height at time t is
h(t) = 144 - 16t²
When t = 0, then h = 144.
Therefore the height from the ground is 144 when the object is dropped.
When the object reaches the ground, h = 0.
Therefore
144 - 16t² = 0
t² = 144/16 = 9
t = 3 s
Answer:
The object reaches the ground in 3 seconds.
Answer: 
Step-by-step explanation:

if it matters then simply further...
4 + \sqrt{4i} = 
Answer:
Standard error = 0.070
Step-by-step explanation:
Formula for the standard error of the distribution of differences in sample proportions is;
σ_(A - B) = √((p_a^(1 - p_a^)/n_a) + (p_b^(1 - p_b^)/n_b))
We are given;
p_a^ = 0.48
n_a = 80
p_b^ = 0.13
n_b = 66
Thus;
σ_(A - B) = √((0.48(1 - 0.48)/80) + (0.14(1 - 0.13)/66))
σ_(A - B) = √0.00496545455
σ_(A - B) = 0.070