• The Length of the Second Train

    A train moving at a speed of 49 mph is passed by a train moving at a speed 63 mph.

    A passenger in the first train noted that the second train took 4.5 seconds to pass

    How long is the second train?


    1. The relative velocity between the trains is 112 mph (63 + 49).
    2. To get the answer we must multiply the velocity times the time.
    3. To get the correct units, convert mph to feet per sec, then multiply times 4.5 sec to get the answer in feet.

    Answer: (5289 x (49 + 63) x 4.5) / (60 x 60) = 740.46 feet.

    The length of the second train is \’740.46\’ feet

  • The Driving School

    A driving school claims an average test pass rate of 76.8 per cent.

    What is the least number of pupils required to achieve this result?


    The answer is 125 as we need 96 passes out of 125 to get an average of 76.8%

  • Manhole Cover

    Why are manhole covers round (or circular)?


    A circular manhole cover is the only geometric shape that will not fall into the hole. šŸ™‚

    Circular manhole covers are easy to carry as we can roll them when needed and also no particular alignment is needed with positioning it over a hole.

  • In The Elevator

    I\’m a security guard in an elevator with two other people. When it reaches the first floor, one person gets out and six get in.

    When it reaches the second floor, three people get out and twelve get in.

    At the third floor, five leave and nine enter.

    It rises to the fourth floor, one person gets on and the doors close.

    Suddenly, the elevator cable snaps and the elevator smashes to the ground.

    No one survives the fall, yet Iā€™m alive and know exactly how many people go on and off the elevator at every floor.

    How is this possible?


    I got off at the first floor. I am a security guard and knew how many people got on and off the elevator by watching the surveillance footage.

  • The Two Trains On the Track

    Two trains are on the same rail road track, one is headed east the other west, they both leave the station at 1:00 and are travelling at the same speed.

    Yet they didn\’t crash into each other.

    How can this be?


    They went at the same time but one went at 1:00 in the afternoon and one went at 1:00 in the morning.