In our widget example, we will assume that the fixed cost for the stapler, pen, and âfactoryâ is $10 and the cost of each worker hired is $5 per worker. Since fixed costs are constant, the firm incurs $10 regardless of the level of output. Labor is the only variable cost computed by $5 times the number of workers.
How Bull Sharks Can Live in Both Ocean and Fresh Water. Although there are a handful of species that live in freshwater, we tend to think of sharks as being ocean dwellers. But there is also a very unique shark that can live in both ocean and fresh water estuaries and lakes: the Bull Shark.
But they do have extra large livers, which provide some buoyancy and help keep them sinking to the ocean floor. But fresh water changes how much buoyancy the shark's liver can provide. The researchers found that when sharks swim in fresh water, they are two to three times less buoyant than when they swim in salt water. In order to keep afloat the same way they do in salt water, sharks would need livers eight times as largeâunrealistic for an organ thatâs already the largest in a sharkâs body.