The distance fallen, s, of a freely falling object is given by the equation . . .
s = 1/2 gt², where g is the acceleration due to gravity.
s = (9.8/2)(t²) = 4.9t²
distance fallen in tenth second = total distance fallen in tenth second - total distance fallen in ninth second . . .
or, s(10) - s(9)
= 4.9(10²) - 4.9(9²) = 93.1 ft