Question

on a 60 km track, a train travels the first 30 km with the uniform speed of 30 km/hr . how fast must the train travel the next 30 km so as to average 40 km/he for the entire trip?​

Answer 1

Answer:

Explanation:

Given,

Total distance = 60 km

Speed in 1st journey = 30 km/h

Average Speed = 40 km/h

To Find,

Speed in 2nd journey = ?

Formula to be used,

Average Speed = Total distance/Total time

Solution,

Putting all the values, we get

Average Speed = Total distance/Total time

⇒ Average Speed = Total Distance/ t₁ + t₂

⇒ 40 = 60/1 + (30/v)

⇒ 40 × (v + 30) = 60v

⇒ 40v + 1200 = 60v

⇒ 1200 = 60v - 40v

⇒ 1200 = 20v

⇒ v = 1200/20

⇒ v = 60 km/h

Hence, the train trave at 60 km/h in next 30 km.

Answer 2

Answer:

Given :-

• Total Distance = 60 km
• Speed = 30 km/h
• Average speed = 40 km/h

To Find :-

Speed of 2ⁿd journey

Solution :-

• Average speed = Total Distance/Speed 1 + Speed 2

40 = 60 + 30/v

40(v + 30) = 60v

40v + 1200 = 60v

1200 = 60v - 40v

1200 = 20v

v = 1200/20

• v = 60 km/h