Due to the departure of environmental stipulations and imperfections in the extent regularity, a unmarried extent procure not fruit the proper space d. The schoolman takes n extents of the space and uses the illustration middle to think the gentleman space. From elapsed archives of these extents the schoolman knows the discord of a unmarried extent is 4m2. How abundant extents should the schoolman fashion so that the fortuity that his think differs by d by over than 0.5 m is at most 0.05?