To find out how many people out of 100 had attended the previous year, you can use a proportion based on the total number of people at the festival.
You have 420 attendees from the previous year out of a total of 600 people. To convert this to a smaller scale (per 100 people), you can set up the following calculation:
\[ \frac{420 \text{ people}}{600 \text{ people}} \times 100 \]
Now, calculate it:
\[ \frac{420}{600} = 0.7 \]
Then, multiply by 100:
\[ 0.7 \times 100 = 70 \]
Thus, out of 100 people at the festival, 70 had attended the previous year.