15. Scientists conduct an experiment, making a record every 5 hours. When making the twelfth record, the hour hand of the clock points exactly to 9. What number did the hour hand point to when they made the first record?
15.【Solution】From the first record to the twelfth record, there are eleven intervals, totaling $5 \times 11=55$ (hours). The hour hand completes one full circle in 12 hours, and the remainder of 55 divided by 12 is $7, 9-7=2$

Answer: The hour hand points to 2.