Answer:
12.7 years to the nearest tenth.
Step-by-step explanation:
The total of the ages for the 25 students = 10*25 = 250.
For the 30 students it is 15*30 = 450.
The average for the 2 classes = (250 + 450) / (25 + 30)
= 700 / 55
= 12.7 years to the nearest tenth.