A cyclist rides a bicycle 7 km at an average speed of 10 km/hr and again travels 10 km at an average speed of 7 km/hr. What is the average speed for the entire trip?
Choose the correct choice from the following:	A) 7.59	B) 7.79	C) 7.99	D) 8.19	E) 8.39

Rationale: distance = 17 km time = 7 / 10 + 10 / 7 = ( 49 + 100 ) / 70 = 149 / 70 hours average speed = ( 17 * 70 ) / 149 = 7.99 km / h the answer is c .
Answer: C