A truck owner buys diesel at Rs.5, Rs. 8 and Rs. 10 per litre for three successive years. What approximately is the average cost per litre of diesel if he spends Rs. 4000 each year?
7.05
No. of litres used in first year = 4000 / 5 = 800, similarly for second and third year is 500 and 400.
Average cost per litre = total cost for 3 years / total litres = (3 x 4000) / (800+500+400) = 7.05.