Mathematics for IGCSE & O level - Proportion (Section 3 - No. 13)
If y is inversely proportional to x^2 and x is doubled, by what factor does y change?
2
1/2
4
1/4
Giải thích
If x is doubled, x^2 becomes 4 times larger. Since y is inversely proportional, y becomes 1/4 of its original value.