How many students? How many countries?

"OneidaDispatch.com" wrote that Hansen left for Brisbane, Australia yesterday, and will spend a week there for the competition. He will compete with students from 160 countries! I confused: Are there this number of countries in the world?
But look what numbers gives "ninemsn" The so-called Olympics of the mind was staged over a week, with a total of 16 gold medals, 32 silver and 48 bronze awarded to some of the 163 students from 42 countries in the event.
Meanwhile reported Yahoo! that approximately 160 students representing 40 countries competed in this rigorous competition in Australia.
But the numbers are like this according to CBC Health & Science News
Wang, Singh and Ralph Zhang of Edmonton competed against 157 other students from 39 countries from July 11 to 18. Zhang didn't place.
By the way, don't forget to read this gossip about Kay Aull, a competitor form USA on this page
And finally: four junior college students won Singapore second place in this year's International Biology Olympiad in Brisbane, Australia!