Question

Shyam went from delhi to shimla via chandigarh by car. the distance from delhi to chandigarh is 3/4 times the distance from chandigarh to shimla. the average speed from delhi to chandigarh was half as much again as that from chandigarh to shimla. if the average speed for the entire journey was 49 kmph. what was the average speed from chandigarh to shimla?

Answer 1

Answer: 70 km/h

Explanation:

Average speed = Total Distance/ Total time taken

Let the distance between Delhi to Chandigarh be d and distance between Chandigarh to Shimla be d'

Then,

⇒d = 3/4 d'

Let the average speed between Delhi to Chandigarh be v and between Chandigarh to Shimla v'

⇒v = 1/2 v'

Average speed for the entire journey, V = 49 km/h

Total distance = d+d' = 3/4d'+d' = 7/4 d'

Total time taken = d/v+d'/v'

∵$\frac{d}{v} = \frac{3/4d'}{1/2v'} =\frac {3d'}{2v'}$

⇒d/v+d'/v' = 5/2 d'/v'

$V = \frac{7/4 d'}{5/2 d'/v'}= 0.7 v'$

⇒v' = 49 km/h ÷ 0.7 =70 km/h

Hence, the average speed from Chandigarh to Shimla is 70 km/h.