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 1 640 of a square mile approximately 4046 856 m 2 or about 40 % of a hectare square enclosing one acre is approximately 69 57 yards or 208 feet 9 inches 63 63 metres on a side as a unit of measure an acre has no prescribed shape any area of 43560 square feet is an acre