Question

4 is to 1 as 1/2 is to?

Answer 1

$4:1:: \frac{1}{2}:\ ? \\ \\ \Rightarrow \frac{4}{1} = \frac{1/2}{?} \\ \\ \Rightarrow 4 = \frac{1}{2 \times?} \\ \\ \Rightarrow ? = \frac{1}{2 \times 4}= \boxed{\frac{1}{8}}$

Answer 2

4:1=0.5:x
4/1=0.5/x
4*x=0.5*1
4x=0.5
x=0.5/4
  =0.125