SOLUTION: The total oil reserve at the Kranka oil field is 250 tonnes. The annual consumption is 20 tonnes which increases by 2% per annum. How long will it take for the oil to be used up?

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Question 1072885: The total oil reserve at the Kranka oil field is 250 tonnes. The annual consumption is 20 tonnes which increases by 2% per annum. How long will it take for the oil to be used up?
Answer by jorel1380(3719) About Me  (Show Source):
You can put this solution on YOUR website!
The initial consumption is 20 tonnes, which increases by 2% per year. To sum up the series, we have:
250=20Σ(1.02)^n where n goes from 0 to ?. 250/20=12.5, so
12.5=Σ(1.02)^n
Plugging in different values for n, we find that n equals a little over 11 years before the oil reserve is used up.