I'm sure the answer is William James.
The answer to this question is 40-60% ; 25%
Other estimation is based not based on the raw intellegence possesed but rather based on whether they could use the intelligence for real life purpose. Studies shows that even though young adults already fully developed the capability for formal operational thinking , onle a quarter of them actually got used to doing it.
The first and most obvious answer to the question of why we're so obsessed with burgers is: burgers are cheap. ... It's not just that burgers are cheap, it's that they're easy to eat. Because the meat is ground up, you don't have to do much chewing. Because it's served on a bun, it's easy to eat.
