A train travels 60 miles at a speed of 30 mph, and then returns the same 60 miles at a speed of 60 mph. What was its average speed for the entire round trip?
40 mph
Total distance is 120 miles. Outbound trip takes 2 hours (60/30). Return trip takes 1 hour (60/60). Total time is 3 hours. Average speed = 120 / 3 = 40 mph.
About this riddle
Math riddles hide a calculation inside a short story. Pull out the numbers, work out what is being asked, and watch for a trick such as a unit change.
Difficulty: Hard. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
More math riddles
A container holds bacteria that double in population every minute. At minute 10, the container is half full. At what minute was the container one-quarter full?
I am a regular three-dimensional polyhedron. All of my faces are congruent squares, exactly three edges converge at every single vertex, and I possess 12 edges in total. What shape am I?
What is the smallest positive whole number that can be divided evenly by all integers from 1 through 5?
A container holds a colony of bacteria that doubles in size every minute. If it takes 60 minutes for the container to become completely full, at how many minutes was the container exactly half full?
Roses cost 2 dollars each. How much do 7 roses cost?
I am a number composed of identical digits. When you multiply me by 3, the product consists entirely of the digit 3. What number am I?