Explanation:

- Let's consider a number, say 'x'.

- Correct calculation: Multiplying by 4 gives the result as 4x.

- Mistaken calculation: Dividing by 4 gives the result as x/4.

- To find the percentage change, use the formula:

$$

\text{Percentage Change} = \left( \frac{\text{Correct Result} - \text{Mistaken Result}}{\text{Correct Result}} \right) \times 100\%

$$

- Substituting the values:

$$

\text{Percentage Change} = \left( \frac{4x - \frac{x}{4}}{4x} \right) \times 100\% = \left( \frac{16x - x}{16x} \right) \times 100\%

$$

$$

= \left( \frac{15x}{16x} \right) \times 100\% = 93.75\%

$$

- Based on this calculation, the option that matches is Option: 4, 93.75%.