1. Buses from Moscow to Voronezh depart every hour, at 00 minutes. Buses from Voronezh to Moscow depart every hour, at 30 minutes. The trip between the cities takes 8 hours. How many buses from Voronezh will the bus that left from Moscow meet on its way?
Answer: 16.

It is clear that all buses from Moscow will meet the same number of buses from Voronezh, and we can assume that the bus from Moscow departed at 12:00. It is easy to understand that it will meet buses that left Oryol at 4:30, 5:30, ..., 18:30, 19:30 and only them. There are 16 such buses.

$\pm$ Correct reasoning with an arithmetic error leading to an incorrect answer. 4-5 points

干 The frequency of encounters (every half hour) was calculated, but the answer is incorrect. 3 points

- Correct answer without explanation. 1 point