Traditional lap pools are about 10 feet wide, though widths between 8 and 10 feet are common. (In competition pools, swim lanes are 2.5 meters wide, or about 8.2 feet.) You don't want to go too narrow with a lap pool.
The number of neurons in the brain varies dramatically from species to species. One estimate (published in 1988) puts the human brain at about 100 billion (10 11) neurons and 100 trillion (10 14) synapses.
Answers: Don't confuse axons with neurons. There are approximately 100,000,000,000 neurons in the human brain. Most of them are support cells and have nutritive, immunologic and protective functions. The number of axons per cell vary, mostly in the types of cells. For example Purkinje cells have many axons and therefore many more connections.