lottery.rb

class Lottery

  def initialize(winners)
    @winners = winners
    @ary = []
  end

  def add(name, weight)
    @ary += Array.new(weight, name)
  end

  def winners
    winners = []
    @winners.times {
      winners << @ary.at(rand(@ary.size))
    }
    winners
  end
end

spike.rb

require './lottery.rb'

lottery = Lottery.new(3)
lottery.add("John", 1)
lottery.add("Tom",  2)
lottery.add("Bill", 5)
lottery.add("Woz",  2)
lottery.add("Ken",  10)

lottery.winners