Logic Puzzle/Questions with "how.."

A2 , B1

Test your logic skills with this puzzle, then see if you know how to make questions with "How". Activity time: 5 to 30 minutes.

Task: Farmer Giles is walking home at 5 km per hour with his dog, Rex. When he is 20 km from home, he lets Rex off his lead and the dog runs back home at an average of 15 km per hour. He then runs back to the farmer, back to the house, and so on and doesn't stop running until the farmer gets home. How far does Rex run in that time? 

Not too difficult? So now try this little challenge: How many different questions can you think of that begin with the word "How...?"  There was one in the puzzle and one in the last sentence. Can you write down at least 12 others?

Check your answers here.