To find out how many megabytes have been downloaded, we can calculate 19.1% of 258 megabytes.
First, convert the percentage to decimal form:
\[ \text{Decimal} = \frac{19.1}{100} = 0.191 \]
Next, multiply this decimal by the total file size:
\[ \text{Downloaded megabytes} = 0.191 \times 258 \]
Calculating this gives:
\[ 0.191 \times 258 \approx 49.278 \]
Now, we round 49.278 to the nearest tenth:
\[ 49.3 \]
Thus, approximately 49.3 megabytes have been downloaded.