Total Cost and Total Revenue at the Raspberry Farm

A perfectly competitive firm takes the market price as given, so its total revenue is a straight line through the origin whose slope is the price: at $4 a pack, 60 packs bring in $240. Total cost starts at the fixed cost of $62 and rises, slowly at first and then more steeply as diminishing marginal returns set in. Profit at any output is total revenue minus total cost, the vertical gap between the two curves; at 60 packs it is $240 − $165 = $75.

Where total cost is above total revenue, at outputs below about 30 or above 100, the farm makes a loss. In between it makes a profit, and the profit curve peaks between 70 and 80 packs at $90. The slider changes the price, which tilts the revenue line and moves the profit range.