In 6 months, Ret needs to purchase a particular commodity. Unfortunately, there are no futures contracts written on that specific commodity. However, futures contracts are available on a related commodity which mature in 6 months. The standard deviation of the spot price is $0.73 and the standard deviation of the futures price is $0.62. What is the optimal hedge ratio for Ret's exposure assuming the correlation of the spot and futures prices is 0.91?