On a journey across Bombay, a tourist bus averages 10 km/h for 20% of the distance, 30 km/h for 60% of it and 20 km/h for the remainder. The average speed for the whole journey was  Answers
A) 10 km/h  B) 30 km/h  C) 5 km/h  D) 20 km/h  E) None of these
explanation   Let the average speed be x km/h.   and Total distance = y km. Then,   0.2⁄10y + 0.6⁄30y + 0.2⁄20y = y⁄x   ⇒ x = 1⁄0.05 = 20 km/h   Answer 20 km/h
<result>D</result>
On a journey across Bombay, a tourist bus averages 10 km/h for 20% of the distance, 30 km/h for 60% of it and 20 km/h for the remainder. The average speed for the whole journey was