A bike owner buys petrol at Rs 75, Rs. 80 and Rs. 85 per litre for three successive years. What approximately is the average cost per litre of petrol if he spends Rs. 40000 each year?  Choose the most appropriate option:
A) Rs 79.8 B) Rs 80.4 C) Rs 85.5 D) Rs 90 E) Rs 60
Explanation :   Total quantity of petrol consumed in 3 years = 40000/75 + 40000/80 + 40000/85 litres   = 40000 (1/75 + 1/80 + 1/85 ) = 40000(767/20,400) = 76700/51 litres   Total amount spent = Rs. (3 x 40000) = Rs. 120000.   Average cost = Rs. 120000 x 51/76700   = Rs. 61200/767   = Rs. 79.8   Rs 79.8nswer : Rs 79.8
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A bike owner buys petrol at Rs 75, Rs. 80 and Rs. 85 per litre for three successive years. What approximately is the average cost per litre of petrol if he spends Rs. 40000 each year?