Mathematics for IGCSE & O level - Proportion (Section 2 - No. 6)
If *p* is inversely proportional to the square of *r* (*p* α 1/*r*2), and *p* = 4 when *r* = 3, find the constant of proportionality.
9
12
36
144
설명
Since p = k/r^2, substitute p = 4 and r = 3, so 4 = k/9, and k = 36.