Question

A train completes a certain journey in 12 hours. It covers half the distance at 40 km/hr and the rest at 60 km/hr. The length of the journey is

Answer 1

Answer:

Required distance is 576 km

Step-by-step explanation:

Let total distance 2p km

then the train complete p km at 40km/hr. speed

∴ for 40 km the train takes 1 hr.

for  p km the train takes p/40 hr.

Again, the train complete remaining p km at 60km/hr. speed

∴the train for 60 km the train takes 1 hr.

for p km the train takes p/60 hr.

Now , p/40 + p/60 = 12

⇒ p/2 + p/3 = 240

⇒5p/6 = 240

⇒ p = 288 km

hence 2p = 576 km

Answer 2

576km

Step-by-step explanation:

we know that with both speeds distance covered is equal and the total time taken is 12hrs

so we make two equations by taking two variable for time x and y

so the equation will be

x+y= 12 (as total time is 12 hrs, x is for one speed and y is for second

second equation will be 40x=60y

after solving these equation with any method we get time taken by 40km/h is 7.2hrs and by 60km/h is remaining time 4.8hrs, and the distance is 288km by each speed, so total speed covered is 576km