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.
The Fastest Shark in the Ocean. The shortfin mako shark is the fastest shark in the ocean. This toothy torpedo can swim at speeds of up to 60 mph has a tail like a tuna fish, its favorite prey.  01:58. Get up close and personal with sharks catching their prey.