A copper producer plans to sell 8,000 tonnes of copper next month in the spot market. The treasurer is worried that the spot price might decline before the sale is made and is considering using copper futures to hedge this price risk. Each futures contract is written on 100 tonnes of copper. The standard deviations of the daily change in the spot price and nearby futures price are 0.22 and 0.24 respectively and the correlation between daily changes in spot and futures prices is 0.80. If the treasurer decides to hedge 86% of their exposure, the number of futures contracts the treasurer should sell is:

ANS = 50 contracts - pls show working