1) A car owner buys petrol at Rs 7.50, Rs. 8 and Rs. 8.50 per litre for three successive years. What approximately is the average cost per litre of petrol if he spends Rs. 4000 each year ? A) Rs. 7.98 B) Rs. 8 C) Rs. 8.50 D) Rs. 9 Answer: Option AExplanation:Total quality of petrol consumed in 3 years = $(\frac{4000}{7.5}+\frac{4000}{8}+\frac{4000}{8.5})$$=4000(\frac{2}{15}+\frac{1}{8}+\frac{2}{17})=\frac{76700}{51}litres$Total amount spend =3x4000=12000.Average cost = $\frac{12000\times51}{76700}=\frac{6120}{767}=7.98$
