If x is the mean of x1 , x2 , ……. , xn and is the mean of y1 , y2 , ….. yn and is the mean of x1 ,x2 , …… , xn , y1 , y2 , …. yn , then z = ?
(A) \(\frac{\bar x+\bar y}{2}\)
(B) \({\bar x+\bar y}\)
(C) \(\frac{\bar x+\bar y}{n}\)
(D) \(\frac{\bar x+\bar y}{2n}\)