Answer:
The average current going down the funnel is 1504 A.
Step-by-step explanation:
Given that,
Magnetic field,

Measurements at a distance of 12.8 km from a large tornado, r = 12.8 km
We need to find the average current going down the funnel. We know that the magnetic field due to current carrying conductor is given by :

I is current

So, the average current going down the funnel is 1504 A. Hence, this is the required solution.