Cuilumber Candle Supply makes candles. The sales mix (as a percmtage of total doliar siles) of its three produxt ines is birthday candies 30 is stardand tagerod candies Sonk and iarge vaceited candles 20% . The contribution eargin ratio of each candle type is shown beiow ( a ) Whist is the weldited- aver age contribution manumatabi? Weishted avecage contribution maren ration .