中會kieso ifrs版本第11章的問題 - 會計

題目如下,不懂的地方在於,為何租金的單位成本是除以18000,而非估計的250000桶呢?

Federer Drilling Company has leased property on which oil has been discovered.
Wells on this property produced 18,000 barrels of oil during the past year
that sold at an average sales price of $65 per barrel. Total oil resources
of this property are estimated to be 250,000 barrels.

The lease provided for an outright payment of $600,000 to the lessor (owner)
before drilling could be commenced and an annual rental of $31,500...

From the provisions of the lease agreement, compute the cost per barrel for
the past year, exclusive of operating costs, to Federer Drilling Company.

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