Subject: How does 23.5 degrees = 23 degrees 27' ?

I research and write questions for a trivia game at a local pub.  One of last 
week's questions was: How many degrees north of the equator is the Tropic of 
Cancer?  In the several places I checked, the answer 23.5 degrees was given.  
One of the contestants gave the answer 23 degrees, 27', which is apparantly 
correct.  I also found sources that said it's 23 degrees, 30'.

Does this mean that one "degree" is 54'?  I looked up the definition 
of "degree", and found that it is 1/360 of a circle, but 1/360 = 0.002778.  I 
also did some research on your site, and did a bunch of math, and came up with 
one degree equalling 4'.  I can't figure out the relationhip between a degree 
and a minute (is the single apostrophe a symbol for "minute" in this 
context?).  

I'm just curious.  Please help.  Thank you!

Re: How does 23.5 degrees = 23 degrees 27' ?