Q: The private costs and externality costs (damage to crops along tracks) for trains is provided below. If the revenue per train (that is, price (P)) is $350, the market outcome is trains per day. The socially optimal outcome is trains per day. Number of trains Private Costs Crop Damage per day $100 $200 $200 $400 $400 $600 $700 $800 $1 100 $1000 6 $1600 $1200