To find when the object will fall back to the ground, we need to find the time when s(t) = 0.
0 = -16t^2 + 11t + 25
This is a quadratic equation that we can solve using the quadratic formula:
t = (-11 ± sqrt(11^2 - 4(-16)(25))) / (2(-16))
t = (-11 ± sqrt(121 + 1600)) / -32
t = (-11 ± sqrt(1721)) / -32
Since we cannot have a negative time for this problem, we can ignore the negative solution and use only the positive solution:
t = (-11 + sqrt(1721)) / -32 ≈ 1.64
Therefore, the object will fall back to the ground after approximately 1.64 seconds. So, the correct answer is:
D. 1.64