To find the relative frequency for the event "spin a 1", you will use the formula:
\[ \text{Relative Frequency} = \frac{\text{Frequency of the event}}{\text{Total number of trials}} \]
From the table you provided:
- Frequency of spinning a 1 = 21
- Total number of trials = 75
Now, plug in the values:
\[ \text{Relative Frequency} = \frac{21}{75} \]
Next, simplify the fraction:
\[ \text{Relative Frequency} = \frac{21 \div 3}{75 \div 3} = \frac{7}{25} \]
Therefore, the relative frequency for the event "spin a 1" is:
\[ \frac{7}{25} \]