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The bottommost of the 10 brackets has the most SSPs, the topmost bracket has the least, and the ratio of the sizes of the bottommost bracket to the topmost bracket is 10. The mean hosting fee is dollars per month.
Let i = bracket index, integer between 0 and 9
Let f[i] = i-th monthly fee
Let w[i] = i-th weight (relative population size)
Let p[i] = i-th population size
Let N = sum p[i] over i = 0 to 9: total no. of SSPs
Let x = sum w[i] over i = 0 to 9
f[i] = 5[1, 10^(1/9), 10^(2/9),..., 10^(8/9), 10]
f'[i] = 1, 10^(1/9), 10^(2/9),..., 10^(8/9), 10
w[i] = 10, 10^(8/9),..., 10^(1/9), 1
p[i] = N(w[i]/x)
Let c[i] = i-th cost = f[i]p[i]
Let t = total = sum c[i] over i = 0 to 9
Let c'[i] = f'[i]p[i]
Let t' = sum c'[i] over i = 0 to 9
Let a' = average fee (based on f', not f) = t'/N
Let a = true average fee = 5a' = 5t'/N
t' = N/x[(10 x 1) + (10^(8/9))(10^(1/9)) + ... + (10^(1/9))(10^(8/9)) + (1 x 10)]
t' = (N/x)100
a' = 100/x
a = 500/x
x = 40.87
a = 12.234