For this case we have the following equation:
h (t) = - 16t ^ 2 + 76t
We must find the time that was in the air.
For this we equate the equation to zero.
-16t ^ 2 + 76t = 0
We look for the roots of the polynomial.
For this, we rewrite:
-4t * (4t-19) = 0
Which roots are:
t = 0
t = 19/4
Therefore, the time it was in the air was:
t = 19/4
Answer:
t = 19/4 seconds