Mathematics for IGCSE & O level - Proportion (Section 1 - No. 28)
If *a* is directly proportional to the square root of *b*, and *a* = 6 when *b* = 9, then find *a* when *b* = 4.
2
4
6
8
คำอธิบาย
a=k√b. Substitute to get, 6=k√9, k=2. a= 2√b; a=2*sqrt(4)=4.