Question

The time it takes to travel to a destination varies inversely with the average speed. It takes two hours when the average speed is 40mph. If the average speed changes to 80mph, what is the new travel time?

Answer 1

Answer:

By inverse proportionality,

40/2 = 80/x

40x = 160

x = 160/40

x = 4

So, new travel time is 4 hour.

Answer 2

4hour.

Justification:

We are given time takes to travel is inversely with an average speed.

• When average speed is 40mph, it takes 2hour.

Then,

If average speed is 80mph, let time taken be x:

• 40/2 = 80/x
• 40x = 160
• x = 160/40
• x = 4

Hence, it takes 4 hour to travel to a destination with 80mph.