Jack and Jill are marathon runners. Jack can finish a marathon (43 km) in 4.5 hours and Jill can run a marathon in 4.3 hours.What is the ratio of their average running speed? (Jack: Jill) Choices.
A) 14 / 15 B) 43 / 45 C) 4 / 5 D) 5 / 4 E) can not be determined

Rationale: "average speed of jack = distance / time = 43 / ( 9 / 2 ) = 86 / 9 average speed of jill = 43 / ( 4.2 ) = 10 ratio of average speed of jack to jill = ( 86 / 9 ) / 10 = 86 / 90 = 43 / 45 answer b"
Answer: B