To determine who spent more time writing per problem, we need to calculate the unit rate (minutes per problem) for both Sonia and Maryna.
For Sonia:
- \( \frac{120 \text{ minutes}}{6 \text{ problems}} = 20 \text{ minutes/problem} \)
- \( \frac{360 \text{ minutes}}{18 \text{ problems}} = 20 \text{ minutes/problem} \)
- \( \frac{500 \text{ minutes}}{25 \text{ problems}} = 20 \text{ minutes/problem} \)
- \( \frac{1200 \text{ minutes}}{60 \text{ problems}} = 20 \text{ minutes/problem} \)
Sonia's unit rate is consistently 20 minutes per problem.
For Maryna:
- \( \frac{200 \text{ minutes}}{8 \text{ problems}} = 25 \text{ minutes/problem} \)
- \( \frac{375 \text{ minutes}}{15 \text{ problems}} = 25 \text{ minutes/problem} \)
- \( \frac{500 \text{ minutes}}{20 \text{ problems}} = 25 \text{ minutes/problem} \)
- \( \frac{1250 \text{ minutes}}{50 \text{ problems}} = 25 \text{ minutes/problem} \)
Maryna's unit rate is consistently 25 minutes per problem.
Now comparing the two:
- Sonia: 20 minutes/problem
- Maryna: 25 minutes/problem
Therefore, the answer is:
Maryna spent more time writing per problem at the unit rate of 25 min. 1 problem.