Remember that "guess the jelly beans in the jar" scenario? Just because you were off by a couple hundred or so doesn't mean that all hope is lost. It's entirely possible to improve guessing abilities, both as it relates to concrete examples like the jelly bean jar, or by accurately surmising other people's intentions/opinions. How? "If you can practice a specific type of guessing and get feedback about your guesses ... your guesses will become more accurate over time," says Michaelis.
There are some steps to take when engaging in an items-in-the-jar contest that can narrow your guessing field. Clark University researchers in Massachusetts found that spherical objects, when put in a container randomly (as opposed to careful packing) occupy about 64 percent of said container [source: Baker and Kudrolli]. Non-spherical objects, like cubes or "peanuts," take up somewhere between 50 and 54 percent of the space. Jelly beans were not studied, but they aren't likely to be any better than the other nonspherical objects because their uneven shapes don't allow them to settle as efficiently as those with evenly distributed sides [source: Schewe].
That's all fine and dandy, but how's a regular person to parlay that into an accurate guess? "First, estimate the size of the jar," says New York University researcher and physics expert Jasna Brujic in a Scientific American interview. "Then look to see if all the candies are the same size. If they are, take 64 percent of that volume and divide it by the size of the candy to get the total number that would randomly fit inside. If they aren't equally sized, divide a slightly larger area, around 70 percent, by the average size of the candies."
So, grab a calculator, a few jars of differing sizes and a couple packs of leftover jelly beans. The formula sounds complex, but will probably be easier to figure after a couple of practice rounds.