A cyclist rides a bicycle 9 km at an average speed of 11 km/hr and again travels 11 km at an average speed of 9 km/hr. What is the average speed for the entire trip?
Choose the most appropriate option: A) 9.3 B) 9.6 C) 9.8 D) 10.1 E) 10.3
distance = 20 km   time = 9/11 + 11/9 = (81 + 121) / 99 = 202 / 99 hours   average speed = (20 * 99) / 202 = 9.8 km/h   The answer is 9.8.
<result>C</result>
A cyclist rides a bicycle 9 km at an average speed of 11 km/hr and again travels 11 km at an average speed of 9 km/hr. What is the average speed for the entire trip?