Mathematics for IGCSE & O level - Proportion (Section 1 - No. 48)
If *y* is jointly proportional to *x* and *z* and *y* = 30 when *x* = 2 and *z* = 3, find *y* when *x* = 4 and *z* = 5.
50
75
100
150
คำอธิบาย
y=kxz. 30=k*2*3, k=5. Therefore y=5*4*5=100.