Answer
$S'(100)\approx 0.36$
In $100$ square meters, the number of species varies by the rate of $0.36$ units per square meters.
Work Step by Step
$$S(A)=0.882A^{0.842}$$
$$S'(A)=0.882\cdot 0.842A^{0.842-1}$$
$$S'(100)=0.882\cdot 0.842(100)^{0.842-1}\approx 0.36$$
In $100$ square meters, the number of species $S$ varies by the rate of $0.36$ units per square meter.
