task.rb

  def self.average_task_price(identifier,account)
    tasks = Task.find(:all, :conditions =>  {:identifier => identifier , :account_id => account.id})
    size  = tasks.size
    if size > 0
      totalPrice = completions.inject(0) {|val, tasks| val + task.price.to_f }
      total/size.to_f
    else
      0
    end
  end