coverPlease do NOT post your answers, but do say if you think you have solved the puzzles and how long it took. Solution on Monday.

Fred leaves his house in the morning to go to his office.

Just as he is leaving he sees the reflection of his analog clock in the mirror.

Not realising that he is looking in a mirror, Fred assumes there is something wrong with the clock and rides his bike to work.

He arrives at the office 20 minutes later, and discovers that the office clock shows a time that is 2 hours and 30 minutes later than the time that he saw in the mirror image of his clock at home.

Assuming that the clock at Fred’s office and home were both set to the correct time, what time was it when he got to his office?

I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle(UKhere and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.

32 comments

  1. If Fred is not bright enough to realise he is looking in a mirror, can we assume he is bright enough to hang his clock at home the right way up?

    It is a pity that digital clocks were not invented first then perhaps nobody would have seen the need to invent an analog clock and confuse Fred. This would also have saved hours of children’s time learning how to read them, which could be better spent on all manner of things that Michael Gove thinks are not important.

  2. I think there are two solutions, one being quite late (afternoon shift maybe?).

    Have you used the information about the 20 minutes ride? I haven’t, but it makes me wonder if my solutions are wrong…

  3. Not got an answer because I’m feeling thick. May have something after I walk the dog. However, Many years ago, I had an alarm clock that was perfectly square with a round face, and only line markings for the points on the clock face ( I for every 5, and II for every 15 minutes). I woke up one Sunday, and read the clock while on my side, and didn’t correct the time for the fact that I was 90 degrees from where the top of the clock was.

    I jumped out of bed and hurriedly got dressed (thought I was late for work), and put on my (digital watch), and walked to work, only to arrive 2 hours early. I had looked at my wrist watch, but only registered the minutes .reading and never the hours reading.

  4. A proper puzzle without semantic trickery today, and I believe I have the solution, which toook me a couple of minutes. However in reality clock-faces viewed in the mirror do not have the hands in positions that can exist for correct clock faces, except at the hour and half hour, and Fred would have had to overlook the apparent misalignmetn of the hour hand.

    1. Not true, Ivan. At any time, an analog clock image in the mirror would show a perfectly correct time. Example: 1:15 would look like 10:45 in the mirror. In the real world, the hour hand would be 1/4 of the way between 1 and 2, and in the mirror it would be 3/4 of the way between 10 and 11. In both cases, it’s in the right place, corresponding to the minute hand.

  5. Fred assumes there is something wrong with the clock and rides his bike to work.
    I’d have taken it at (clock)face value and gone back to bed.

  6. Maybe I’m just dense but I don’t see how this can be solved.
    If it had said that Jeff reads his clock in the mirror and assumes it’s correct then sure, but if he assumes there is something wrong with it, how wrong does he think it is? Is it fast or slow and by how much?

    1. Fred doesn’t need to know what time it really is when he leaves. He sees the clock, assumes it’s nuts, and just gets on his bike and goes to work.

  7. two valid solutions, since the puzzle specifies that “Fred leaves his house in the morning” but does not specify when he arrives.

    1. I presume you mean that it took you a further 30 minutes to arrive at your second solution.

  8. I even found more than one answer, but assume one two are valid answers
    took me 1 min for the first, and another four for the others.
    (Five minutes Staring at my clock whilst imaginary turning the hands)

  9. Oops, I spent enough time double checking my answer to forget the line ” Fred assumes there is something wrong with the clock”.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s