Solution
= Solution
Only $n=1,2,3$ have $E_n<10c$. The printed squared coefficients sum to $S=0.1^2+0.4^2+0.3^2+0.86^2=0.9996$, rather than exactly one. Normalizing those numbers gives
$$
\boxed{P(E<10c)=\frac{0.01+0.16+0.09}{0.9996}=0.260104\ldots\simeq26.0\%.}
$$
Treating the coefficients as rounded values of an already normalized state gives the intended approximately $0.26$ answer. Probabilities are sums of squared amplitudes because the <energy eigenstates> are <orthonormal>.