Mathematics for IGCSE & O level - Proportion (Section 1 - No. 5)
If *z* varies jointly as *x* and *y*, and *z* = 12 when *x* = 2 and *y* = 3, find *z* when *x* = 4 and *y* = 5.
10
20
30
40
설명
z = kxy, 12 = k(2)(3), k=2. When x=4 and y=5, z= 2 * 4 * 5 = 40