Question

On a 60km State road up bus travel the first 30 kilometre with a uniform speed of 30 km h -1 how fast must the bus travel the next 30 km so as to have average speed of 40 km h -1 for the entry trip​

Answer 1

Given:

• Total distance = 60 km
• Speed of bus of first 30km = 30 km/h

To find:

• Speed of bus of second 30km where the average speed becomes 40km/h

Solution:

Average speed = 40km/h

Using the formula

Average speed = 2V1V2/V1 + V2

Substituting

• V1 = 30 km/h
• V2 = ?

→ 40 = 2(30)(V2)/30 + V2

→ 40/1 = 60V2/30 + V2

By Cross-multiplyng

→ 60V2 = 40(30 + V2)

→ 60V2 = 1200 + 40V2

→ 60V2 - 40V2 = 1200

→ 20V2 = 1200

→ V2 = 1200/20

→ V2 = 60 km/h

Hence , the speed in second 30km where it's average speed becomes 40km/h = 60km/h.