A shop that makes candles offers a scented candle, which has a monthly demand of 345 boxes. Candles can be produced at a rate of 36 boxes per day. The shop operates 20 days a month. Assume that demand is uniform throughout the month. Setup cost is $57 for a run, and holding cost is $1.81 per box on a monthly basis.
What is the Optimal run (production) time (Hint: This will require the use of EPQ formula)?