Answer:
15 seconds
Step-by-step explanation:
Because the split id 25% and 75%, we could create another average pretending that there are four kids, one who ran in 12 seconds, and three who ran in 16.
Equation for averages: (a₁ + a₂ + a₃ + ... [tex]a_{n}[/tex])/ n
Plug in: (12 + 16 + 16 + 16)/4
Add: 60/4
Divide: 15 seconds