Solution
= Solution
{c}
The $2^n$ component intervals are pairwise disjoint and each has length $q_n/2^n$. <Finite additivity> of <Lebesgue measure> gives
$$
\boxed{m(C_n)=2^n\frac{q_n}{2^n}=q_n.}
$$
Their endpoints do not cause overlaps, because the central gaps have strictly positive length.