To find the relative frequency of selecting a heart, we can use the following formula:
\[ \text{Relative Frequency} = \frac{\text{Number of hearts selected}}{\text{Total number of trials}} \]
From the table, we see that the number of trials (total selected cards) is 40, and the number of hearts selected is 14.
Now we can calculate the relative frequency:
\[ \text{Relative Frequency of hearts} = \frac{14}{40} = 0.35 \]
To express this as a percentage, we multiply by 100:
\[ 0.35 \times 100 = 35% \]
So, the relative frequency of selecting a heart is 35%.