Six Sigma is a set of techniques and tools for process improvement. It was introduced by engineer Bill Smith while working at Motorola in 1986. Jack Welch made it central to his business strategy at General Electric in 1995. Today, it is used in many industrial sectors.
One acre equals 0.0015625 square miles, 4,840 square yards, 43,560 square feet or about 4,047 square metres (0.405 hectares) (see below). While all modern variants of the acre contain 4,840 square yards, there are alternative definitions of a yard, so the exact size of an acre depends on which yard it is based.
The acre is a unit of land area used in the imperial and US customary systems. It is defined as the area of 1 chain (22 yards) by 1 furlong (220 yards), which is exactly equal to 1â640 of a square mile, approximately 4,046.856 m 2, or about 40% of a hectare.erhaps the easiest way for US residents to envisage an acre is as a rectangle measuring 88 yards by 55 yards (1â10 of 880 yards by 1â16 of 880 yards), about 9â10 the size of a standard American football field.