The statement is true or false:
(i) If `x` varies directly to `y`, then `xy =` constant.
(ii) If `A` varies inversely with `B`, then `A` varies directly with `1/B`.
(iii) If `A \propto C` when `B=` constant and `A \propto 1/B` when `C=` constant, then, `A \propto C/B` when `B` and `C` both vary.
(iv) If `x \propto 1/y`, then `(xy)^n =` constant.
(v) If `y \propto 1/x`, then, `y/x=` non-zero constant.
(vi) If `a \propto b, b \propto 1/c, c \propto d`, then `a` is inversely proportional to `d`.
(vii) If `x^2 \propto y`, then `y^2 \propto x`.
(viii) If `x \propto y^{3/2}`, then `y \propto x^{2/3}`.
(ix) If `x \propto z` and `y \propto z`, then `xy \propto z`.
(x) If `a \propto b` and `b \propto c`, then `(a+b) \propto c`.