After teaching his class all about Roman numerals (X = 10, IX=9 and so on) the teacher asked his class to draw a single continuous line and turn IX into 6. The teacher's only stipulation was that the pen could not be lifted from the paper until the line was complete.
Cristina learnt how to ride a horse recently. Just to test her skills, she rode the horse from her home to a mine which she covered in three minutes and returned home from the same path only this time she took four minutes. The reason was that while riding away from home, she was supported by the wind however while riding back, she was riding against the wind.
How fast do you think she could have ridden a mile if there was no wind?