RELAZIONI E FUNZIONI PRACTICE WITH CLIL The hydrocarbon reserves At the beginning of 1999, an approximate estimate of the oil and gas reserves from the Norwegian Continental Shelf was calculated at 13 billion tons. This year, around 250 million tons have been produced. How long before we run out of resources if the production is maintained at the same levels of production as in 1999? In alternative, suppose the production is reduced of 2% each year, starting from 2000. In this case, how long will the reserves last? [K. Sydsaeter, P. Hammond, Manuale di matematica per l analisi economica, Vita e Pensiero Editore, Milano, 2004] 216