In what number system?
Congrats, you just gave an incorrect answer to a 15 year old thread!
Base 4, duh! Or Base 9! Or Hex! Or base 25! (Sensing a pattern?)
But definitely not base 10. I think our new friend forgot a zero and is thinking of 100^2, which is 10,000 and not 1,000.
Without reading the rest of the thread: he likes 900 because he likes square numbers and, of those presented, 900 is the only square (30^2)
Well yes, but at least now after 15 years we finally know who’s not getting into Mensa. 
Agree with the poster up-thread who so long ago said that far too many of these things are really tests of “who thinks most like the test author” rather than tests of IQ or knowledge.
For best results it’s very, very important to not have much more or less IQ than the test writer. Also to not have much more or less education than the test writer.
If the test writer leaves Salt Lake City going west at 500 MPH, and you leave Beijing going south at negative 9000 miles per hour, what are the chances you will pass the test?
I remember taking a test a long time ago in which one of the questions was "which of these metals is not like the others: Gold, Aluminum, Silver, Iron " I realized that the answer they wanted was “Gold,” because of it’s color, but the answer could have also been “Iron,” because it was the only one of the four that was ferromagnetic.
Also, aluminum is the only one of those four that is not a transition metal.
Aluminum, because it’s the only one whose chemical symbol matches the name of the element in English.
Oh, that’s another good one. I actually like that answer better than “gold, because of its color.” Do we actually know the answer the test maker expected?
If there’s more than one answer that can be plausibly reasoned into, then it’s a bad question. Those get tossed in more-rigorous environments than the sort of Facebook link that the OP question apparently comes from.
I have a different take on the answer. I think the answer is 1200. It is based on the combination of the question and answer choices. Like most of these type questions, it doesn’t require you to be clever with math but clever with patterns.
John likes a number but does not like the result if the first digit is decremented by 1.
So looking at the possible solutions, you can eliminate all but 1200. He wouldn’t like 900 because 1000 is also a choice, wouldn’t like 1000 because 1100 is also a choice, and wouldn’t like 1100 because 1200 is also a choice. Therefore, only 1200 could be the answer.
OK, so we’ve established that gold, iron, and aluminum are each different from the other three in at least one plausible way.
Can we establish a plausible way that silver differs from the other three? Chemistry is by far my weakest area.
And if we can’t, doesn’t that prove that silver is the correct answer because, unlike the other three, there’s no plausible way to partition the four metals into silver vs the others. :smack:
Stupid / ignorant / blinkered test authors cost me a lot of frustration in school. When I am Emperor they will pay the price for their foolishness. Bwah ha ha ha!!!
Another one for iron is that iron is the only one of those four whose chemical symbol does not begin with “A.”
Iron is the only one which has never been a precious metal; aluminium extraction methods were historically poor, and it was worth more than gold until the 1800s.
The weird thing is, I really don’t know which one of these is the most likely answer that the test taker intended. I’m not sure I like the answer “gold.” I would personally bet on “aluminum,” for the reasons given by DrCube. That kind of seems more like the type of answer a test maker would be going for, at least in my experience.
Much higher electrical conductivity.
Unclear, multi-answerable, or simply wrong questions are the constant curse of trivia players, too.
In base 4, base 9, base 16, base 25,…, also base 900.
1000 in base b is b^3 and hence is a square if and only if b is.
There are lots of ways to simply pick “Which substance of the four has the most extreme value for property X?”. In fact there are as many ways as there are identifiable properties X. A problem with that approach is that while silver has the highest conductivity iron has the lowest. Which extreme is more “natural” to be interested in? So for N properties we now have 2N ways to select the most interesting. That seems to me to be uninteresting.
So what we need is a property where one substance is a clear outlier and the other three substances are nearly indistinguishable on that same property. We’ve got examples for gold, aluminum, and iron already. Now we need silver as the outlier.
Maybe “Which substance(s) have the Hunt brothers tried to corner the market on?”
As to conductivity specifically … I checked here Electrical resistivities of the elements (data page) - Wikipedia for resistivities (1/conductivity). At 20C we get these values in nano-ohmmeters:[ul][]Silver: 15.87[]Gold: 22.14[]Aluminum: 26.5[*]Iron: 96.1[/ul]Given those values I’d say that shows iron is the odd man out and the others are fairly tightly clustered. Although they’re far from indistinguishable, so IMO I would not choose conductivity as a good example of a 3 vs 1 property. Unlike color or ferromagnetism. YMMV.
That doesn’t work, because the answer choices are not part of the question. Under your criterion, would John like 1,000,000? There’s no way to say, which means that you don’t actually have a criterion. This question is unambiguous, because while you can come up with properties that match any answer choice you choose, being a perfect square is by far the most interesting of those properties.
The metals one, though, is a terrible question, because there are equally-sound arguments for multiple answers. Gold is an outlier in its color, iron is an outlier in its conductivity and magnetism, and aluminum is an outlier in its chemical properties and melting point. Their densities vary significantly, too, and either gold or aluminum can be considered the biggest outlier there, depending on whether you consider it linearly or geometrically.