To calculate the percentage of youths who prefer reading electronic books, we first need to determine the total number of youths surveyed.
The number of youths who prefer electronic books is given as 40. The number of youths who prefer printed books is 34. Therefore, the total number of youths surveyed is:
\[ 34 + 40 = 74 \]
Next, we can calculate the percentage of youths who prefer electronic books by using the following formula:
\[ \text{Percentage} = \left( \frac{\text{Number of youths who prefer electronic books}}{\text{Total number of youths}} \right) \times 100 \]
Substituting in the values:
\[ \text{Percentage} = \left( \frac{40}{74} \right) \times 100 \]
Now, performing the division:
\[ \frac{40}{74} \approx 0.5405405405 \]
Now, multiplying by 100 to convert to percentage:
\[ 0.5405405405 \times 100 \approx 54.05405405 \]
Finally, rounding to the nearest tenth of a percent, we get:
\[ \text{Percentage} \approx 54.1% \]
Thus, the percent of youths surveyed who prefer reading electronic books is 54.1%.