6.令X是某一產品的壽命且其服從N(μ,1296)。現在我們隨機挑選n=27個產品,並測試它們,直到其壞掉,得到了樣本平均數=1478小時。請計算μ的95%的信賴區間(10%)

1. (10%) A lower triangular array A is an n-by-n array in which A[]0]== 0, if i <j. Assume that A is stored in one-dimensional array B sequentially, i.e, B[0] = A[0[0], B[1]=A[I][O], B[2] =AI] [1],B[B3]=A[2][0], B[4]=A[2][1], B[S]=A[2][2]J.... Write the addressing formula for the element A[/]U] stored in B[k] in the lower triangular part.