If 10 litres of an oil of Rs.40 per litres be mixed with 5 litres of another oil of Rs.66 per litre then what is the rate of mixed oil per litre?  Choose the most appropriate option.
A) rs . 48.66	B) rs . 51.03	C) rs . 54.17	D) rs . 55.33	E) none of the above

Rationale: "40 * 10 = 400 66 * 5 = 330 730 / 15 = 48.66 answer : a"
Answer: A