Medicine is not for everyone. Choosing to pursue a career in medicine for prestige or financial rewards will likely be disappointing, as most physicians find that medicine is a vocation that requires a commitment to service, lifelong learning and the dedication to practice competently and compassionately.
Though in many European orchards the number of trees per acre is set at 5,000 trees or more, in the US the apple tree density starts at 450-485 trees per acre with a maximum of 1,100 trees/acre. This is a recommended number for the dwarf apple trees.
Of course, they need enough room to breathe and get sufficient sun, which will vary from one cultivar to another. You can plant full-size apple trees 30 to 35 feet apart, semi-dwarf apple trees 20 to 25 feet apart and dwarfs as close as 15 to 20 feet apart. Just be sure to follow the proper pruning techniques for your species. Apples are also picky about their growing climate.