1. In Grandfather Frost's magical forest, cedars grow one and a half times taller than firs and grow for 9 hours. Firs grow for 2 hours. Grandfather Frost planted cedar seeds at 12 o'clock and fir seeds at 14 o'clock. At what time were the trees of the same height? (The trees grow uniformly for the specified number of hours and do not grow any further after that).

Answer: 15 or 18 hours.
Solution: Let the cedars grow to a height of 9 meters, then the firs - 6 meters. In 1 hour, cedars grow by 1 meter, and firs - by 3 meters. At 2 PM, the height of the cedars was 2 meters, and at 3 PM both cedars and firs reached a height of 3 meters. At 4 PM, the firs stopped growing and at 6 PM the cedars caught up with them.

Criteria. Only the answer - 3 points. Only one variant indicated - with justification - 4 points, without justification - 1 point.