Mathematics for IGCSE & O level - Proportion (Section 2 - No. 30)
If *z* is directly proportional to *x* and the square of *y*, and *z* = 24 when *x* = 2 and *y* = 3, what is *z* when *x* = 3 and *y* = 2?
8
12
16
24
解释
z = kxy^2. 24=k*2*9, k = 4/3. Then z=(4/3)*3*4 = 16