Question

A car travels at a constant 40km/h speed for 80km. It then speeds up to 60 km/h another 120
km. What is the car’s average speed for the 200 km trip?

Answer 1

Given data:-

• A car travels at a constant 40km/h speed for 80km.
• Speeds up to 60 km/h another 120km.

Solution:-

{According to given}

Case 1 :-

—› Speed = 40 km/hour

—› Distance = 80 km

—› Time = ?

We use formula of speed to find time:-

—› Speed = {Distance}/{Time}

—› 40 = 80/{Time}

—› 40/80 = 1/{Time}

—› 1/2 = 1/{Time} i.e.

—› Time = 2 hour

Case 2 :-

—› Speed = 60 km/hour

—› Distance = 120 km

—› Time = ?

We use formula of speed to find time:-

—› Speed = {Distance}/{Time}

—› 60 = 120/{Time}

—› 60/120 = 1/{Time}

—› 1/2 = 1/{Time} i.e.

—› Time = 2 hour

from case 1 & case 2

—› Average speed = {Total distance}/{Total time}

—› Average speed = {80 + 120}/{2+2}

—› Average speed = 200/4

—› Average speed = 50 km/hr

Hence,the car’s average speed for the 200 km trip is 50 km/hr.