Q256
A car travels the first one-third of a certain distance with a speed of 10 km/hr, the next one-third distance with a speed of 20 km/hr, and the last one-third distance with a speed of 60 km/hr. The average speed of the car for the whole journey is :
A.
18 km/hr
AnswerB.
24 km/hr
C.
30 km/hr
D.
36 km/hr
Answer: Option A
Solution
Answer: Option A
Solution:
Let the whole distance travelled be x km and the average speed of the car for the whole journey be y km/hrThen,