p varies directly as the square of q and inversely as r. If p = 36, when q = 36, when q = 3 and r = 4, find p when q = 5 and r = 2

A.
72 
B.
100 
C.
90 
D.
200 
E.
125
Correct Answer: Option D
Explanation
P (alpha) (frac{q^2}{r})
P = (frac{kq^2}{r})
k = (frac{pr}{q^2})
= (frac{36 x 4}{(3)^2})
p = (frac{16q^2}{r})
= (frac{16 times 25}{2})
= 200