A seafood stall buys its fresh fish from a local supplier at $4.20 per kg and resells them at $5.70 per kg. Daily demand of the fish can be estimated by a Normal* distribution with a mean of 80 kg and a standard deviation of 10 kg. At the end of each busy day at closing, any unsold fish will be sold to a local producer of cat food at the price of $2.4 per kg. What should be the recommended fish stocking level for this stall?