Instead of multiplying a certain number by 6, Júlia got distracted and divided the number by 6. The error made by Júlia was approximately:
(a) $100 \%$;
(b) $97 \%$;
(c) $83 \%$;
(d) $17 \%$;
(e) $3 \%$.
The correct option is (b).

Solution 1: Let $x$ be the number that Julia got distracted with. She should have obtained $6 x$ but, due to her distraction, she obtained $x / 6$. Therefore, her error was $6 x - x / 6 = (35 / 6) x$ and, in percentage terms, her error was $\frac{(35 / 6) x}{6 x} = \frac{35}{36} \approx 0.9722 = 97.22\%$.

Solution 2: If $N$ is the value that Julia should have obtained, then with her error, she found $N / 36$, so the absolute error committed was $N - N / 36 = (35 / 36) N$ and, therefore, the relative error was $\frac{35}{36} \times 100\% = 97.22\%$.