A train travels 290 km in 4.5 hours and 400 km in 5.5 hours.find the average speed of train.	Select.
A) 80 kmph	B) 69 kmph	C) 70 kmph	D) 90 kmph	E) none of these

Rationale: "as we know that speed = distance / time for average speed = total distance / total time taken thus , total distance = 290 + 400 = 690 km thus , total speed = 10 hrs or , average speed = 690 / 10 or , 69 kmph . answer : b"
Answer: B