SATMathematics Practice Test 1

Since $\frac{\mathit{a}}{\mathit{b}}=2$, it follows that $\frac{\mathit{b}}{\mathit{a}}=\frac{1}{2}$,
Multiplying both sides of the equation by 4 given $4\left(\frac{\mathit{b}}{\mathit{a}}\right)=\frac{4\mathit{b}}{\mathit{a}}=2.$
Choice A is incorrect because if $\frac{4\mathit{b}}{\mathit{a}}=0,$ then $\frac{\mathit{a}}{\mathit{b}}$ would be undefined.
Choice B is incorrect because if $\frac{4\mathit{b}}{\mathit{a}}=1$,then $\frac{\mathit{a}}{\mathit{b}}=4$.
Choice D is incorrect because if $\frac{4\mathit{b}}{\mathit{a}}=4$ then $\frac{\mathit{a}}{\mathit{b}}=1$