Jennifer is 21 years older than her son Douglas. 6 years from now, Jennifer will be 5 times as old as Douglas.

Question: Where is Jennifer's husband most likely to be right now?

  • 19
    $\begingroup$ This really is more of a joke than a puzzle. $\endgroup$
    – xnor
    Mar 18, 2015 at 21:04
  • 3
    $\begingroup$ @xnor Well, it does have a clear solution as to the ages of Jennifer and Douglas. And in the original version, there was a "where is he most likely to be?" disclaimer, which cuts out a lot of the nitpicks from the two joke answers below. $\endgroup$ Mar 19, 2015 at 0:37
  • 3
    $\begingroup$ Jennifer's husband is fishing in Canada. (with apologies to Raymond Smullyan) $\endgroup$
    – David
    Mar 19, 2015 at 2:14
  • 9
    $\begingroup$ Perhaps the puzzle could be improved by changing the final question to "Where is Douglas's father?" $\endgroup$ Mar 19, 2015 at 5:47
  • 1
    $\begingroup$ The original question was not phrased well. I had edited it to resolve that, not realizing the importance of the "most likely" part. I've edited again, restoring that key aspect of the question. :) $\endgroup$
    – JakeRobb
    Mar 19, 2015 at 14:18

3 Answers 3


Let's define $J$=Jennifer and $D$=Douglas.
The problem can be rewritten as:


According to my math, Douglas is $D=(-\frac{3}{4})$ years old, which means $-9$ months. Pregnancy lasts for nine months, so Jennifer's husband is in the bed with her right now.

  • 19
    $\begingroup$ That's actually the milk man.. $\endgroup$
    – blakeoft
    Mar 18, 2015 at 18:18
  • 2
    $\begingroup$ Actually, you can't know yet whether Douglas is a male or a female... $\endgroup$
    – leoll2
    Mar 18, 2015 at 18:21
  • 19
    $\begingroup$ actually they may not be in bed. But he's most probably inside her $\endgroup$
    – Novarg
    Mar 18, 2015 at 19:05
  • 4
    $\begingroup$ @leoll2 - "Actually, you can't know yet whether Douglas is a male or a female". Yes, and I can imagine some feminist visiting this post and calling all of us "male chauvinist pigs". :P $\endgroup$ Mar 19, 2015 at 5:06
  • 8
    $\begingroup$ To be nitpicky, human gestation averages 280 days. The number of days in 9 months is between 273 and 276, depending on which month you start counting from, so we can really only say Jennifer's husband will be in bed with her - on average - within the next 7 days. And even if you massaged the numbers to pinpoint the day, you can't be sure they are in bed right now, you could be a few hours off due to rounding errors. $\endgroup$
    – Michael
    Mar 19, 2015 at 16:36

Jennifer's husband is busy in business meetings, while Douglas's dad is with Jennifer.

  • 3
    $\begingroup$ I was wondering when someone was going to give this kind of amswer, ahahah $\endgroup$ Mar 19, 2015 at 13:04

As mentioned in leoll2's answer above, the Maths part of the question is the simultaneous solution of the two equations which relate the respective ages of Jennifer and Douglas:

$$J=D+21$$ $$J+6=5(D+6)$$

These provide the answer $D = -3/4$ years, or roughly $-9$ months, which could lead one to conclude what leoll2 concluded.


1) It is not necessary that Jennifer's husband must have necessarily fathered Douglas. (No offence meant, I only mean it is not specified in the puzzle.)

2) Biologically, pregnancy doesn't always have to last 9 months. So, one can not deny the possibility of Douglas being born after 8 and a half months instead of nine.

So, Jennifer's husband could be anywhere in this world, or could even be dead. Particularly, if he hasn't fathered Douglas, and pregnancy did last exactly 9 months, then he must not be around at the time of conceiving (stark opposite conclusion from the same data).

This is not a well designed puzzle. Sorry for being a killjoy :(

  • 6
    $\begingroup$ well you're no fun $\endgroup$
    – basher
    Mar 18, 2015 at 19:44
  • 2
    $\begingroup$ @basher - I know, but I think I'm not oversimplifying :) $\endgroup$ Mar 18, 2015 at 19:47
  • $\begingroup$ Plus, the best part of having rep 1 is an immunity to possible down-votes :P $\endgroup$ Mar 18, 2015 at 19:48
  • 11
    $\begingroup$ -1 The trick of solving a puzzle is understanding the puzzle, this puzzle clearly required thinking in generalized terms and this answer clearly fails at that. And if you actually feel sorry for being a 'killjoy', there is a simple solution: just don't post answers like this ;-) $\endgroup$ Mar 18, 2015 at 23:20
  • 1
    $\begingroup$ Yes, and as mentioned in my other comment, human gestation actually averages 280 days, which is up to a week beyond nine months, depending on which months are included. $\endgroup$
    – Michael
    Mar 19, 2015 at 16:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.