arr = [0.054954087385762455, 0.5093998626512432, 5.880466289995431, 0.8639141517665208, 0.2152490168404071]
sum = arr.inject {|sum, item| sum + item}
tmp = 0
arr.each do |pwr|
tmp = tmp + (pwr / sum - 0.2) ** 2
end
puts tmp # 0.42948006253339877
pp ( arr.inject { |result, item| result + (item / sum - 0.2) ** 2} ) # 0.4473023458029664