Untitled

n = int(input())
h = list(map(int, input().split()))
h_partial_sums = [0] * (n + 1)
h_squares_partial_sums = [0] * (n + 1)
h_cubes_partial_sums = [0] * (n + 1)

for i in range(n):
    h_partial_sums[i + 1] = h_partial_sums[i] + h[i]
    item = h[i] * h[i]
    h_squares_partial_sums[i + 1] = h_squares_partial_sums[i] + item
    item *= h[i]
    h_cubes_partial_sums[i + 1] = h_cubes_partial_sums[i] + item
 
for _ in range(int(input())):
    l, r = map(int, input().split())
    num_items = r - l + 1
    mu = (h_partial_sums[r] - h_partial_sums[l - 1]) / num_items
    h2 = h_squares_partial_sums[r] - h_squares_partial_sums[l - 1]
    d = h2 / num_items - mu * mu
    h3 = h_cubes_partial_sums[r] - h_cubes_partial_sums[l - 1]
    a = d ** (-1.5) * ((h3 - 3 * mu * h2) / num_items + 2 * mu * mu * mu)
    print(a)