if it was 48, 48/2+0,5 = 24,5, which is incorrect
same goes for 14 - half of 14 is 7 and when you add 1/2 to it = 7,5
the answer is 7:
1/2 * 7 = 3,5 + 1/2 = 4
then 3 * 1/2 = 1,5 + 1/2 = 2
then the last one left - 1 * 1/2 = 0,5 + 1/2 = 1
so it's 4, 2, 1
Your riddle: You don't say anything? So it's neither true, nor false. But... no, that's not an option - the vampire has all eternity to wait for the man's answer, but a normal human would die after a few days because of dehydration.
Soo... the man has to say a paradox - for example "Everything I say is a lie" - if this is true, then the statement is a lie as well, which isn't possible. If it's false, then he always speaks the true, but he just lied - also impossible