the average of 6 observations is 11 . a new observation is included and the new average is decreased by 1 . the seventh observation is ?
"let seventh observation = x . then , according to the question we have = > ( 66 + x ) / 7 = 10 = > x = 4 . hence , the seventh observation is 4 . answer : a"
subtract(multiply(subtract(11, 1), add(6, 1)), multiply(11, 6))