3.96 ft
Explanation:
An freely-falling object dropped from a certain height travels a distance equal to
h = -16t^2
where t is the time elapsed. So after 1.3 s, the ball has traveled
h = -16(1.3)^2 = -27.04 ft
This means that after 1.3 s, the ball is 31 - 27.04 = 3.96 ft above the ground