A bike owner buys petrol at ₹64, ₹80 and ₹320 per litre for three consecutive years. What is the average cost per litre of petrol if he spends ₹32000 each year?

₹96

Petrol consumption in 1st year = \(\frac{32000}{64}\)  = 500 litres

Petrol consumption in 2nd year = \(\frac{32000}{80 }\)  = 400 litres

Petrol consumption in 3rd year = \(\frac{32000}{320}\)  = 100 litres

Total petrol consumption in 3 years = 500 + 400 + 100 = 1000 litres

Average cost = \(\frac{3 × 32000 }{1000}\)  = Rs96