Mathematics for IGCSE & O level - Proportion (Section 3 - No. 10)
If *y* is directly proportional to the square root of *x*, and *y* = 8 when *x* = 4, find the value of *y* when *x* = 16.
4
8
16
32
คำอธิบาย
y=k√x. 8=k√4, k=4. y=4√x, and if x=16, then y=4*4=16.