[OK] We use cookies to personalise content and adverts. We also share information about your use of our site with our advertising partners who may combine it with other information you’ve provided to them or they’ve collected from your use of their services. You also agree to our terms and conditions (T&C).

Last week I travelled from London to Leeds, which is a distance of 174 miles.

I started at 9.15am and completed the journey with an average speed of 40 miles per hour.

On the way back, in the evening, I travelled exactly the same route, starting at 5.15pm. The traffic was light and I completed the journey with an average speed of 60 miles per hour.

What was the overall average speed for round trip?

The answer is not 50 mph.

Time  = Distance ÷ Speed
Speed = Distance ÷ Time

The outward journey took 174 miles ÷ 40 mph = 4.35 hours.

The return journey took 174 miles ÷ 60 mph = 2.9 hours.

So I travelled a total of 2 x 174 = 348 miles. I did this in a total of 4.35 + 2.9 = 7.25 hours.

My overall average speed was therefore 348 miles ÷ 7.25 hours = 48 miles per hour. QED.

Back to the puzzles...

Our Favourite Illusions

 Shadow Illusion What Am I? Hidden Faces Impossible Waterfall? Same Eyes? Impossible Prongs?
 Duck Or Rabbit? Spinning Dancer Who Turned To? Blind Spot The Butterfly Parallel Cafe Wall Lines?