Update: Thanks to all the people who have linked to this page. Here’s a list of linkbacks. I’ll expand it as I discover new pages linking back to me.
These are the correct answers to the “Prove your logic” test on proveyourlogic.com. It’s not really an iq test, but it took some some thinking nevertheless. I wonder who’s behind the test anyway.
1) money (or nothing) 2) t 3) first 4) five 5) anchor (or net) 6) thursday 7) water 8) 2 9) 6 10) Gregory 11) 999 12) 3 13) 2 14) mother 15) maid 16) m 17) e 18) 13 19) 28 20) Everest 21) 25 22) August 23) 8000 24) 35 25) 59 (Last question)
Explanations to some of the answers may come at a later date. Because of the lare number of new visitors because of this post, I’ve decided to write a tutorial for the test with explanations for each question.
- If you put the word money (Or the word nothing) into the sentences, they’ll be correct. (According to some logic)
I don’t personally agree with the idea that “nothing is better than god”, being an atheist. (Unless the sentence is read as believing in nothing is better than believeing in god)
Also, the sentence 2 and 3 become flawed if you insert “nothing”, because of a double negation.
But nevertheless, these are the working answers for that question.
- The first letters in the English words for the numbers 1-10 (One, two, three,… ten)
- The date July 20th, 1929 occured before the Second World War, thus there was nothing such as a “First World War”, there was only “The world War”. (Or rather The Great War, as it was called in most of the world at the time. Thanks Vince for noticing.)
- Count the number of letters inthe words. For seven, this is obviously 5.
- An anchor is something you throw in the water when you need to use it, and then pick up when you set asail again.
- Since the rules don’t allow that they both lie on the same day, (Yesterday) one of them must be lying today. Thursday is the only possible day. (The hunter told the truth yesterday, but is lying today, so he says he was lying yesterday. The fisherman is telling the truth when he’s saying he lied yesterday.)
- No matter how much dry food you take with you, you will die without water.
- I was later told that the purpose of this riddle was to count the number of loops in the digits. So the values of the digits on the left side are: 0=1, 6=1, 8=2, 9=1, all other digits=0. Also note how the avoided the digit 4 on the left side, since it can be written in either closed or open loop.
However, my way of solving it was a more bruteforce way, where I looked at the equations as a linaer equation system where every number on the right side is the symbol for an unknown variable. So I could easily read out zero-valued symbols from the equations with 0 on the right side. (With the assumption that every symbol could only take on a 0 or positive integer value) So from the given equations 2222=0, 5555=0, 1111=0, I could deduct that 2=5=1=0. Then from a little work I was able to see that 8=2 and I was able to get the answer.
- I actually don’t get why this question is supposed to ne hard but, anyway, there are 6 F’s in that sentence.
- The 4th kid is not named after a month. The key point here is the sentence “His mother have 4 kids” (Bad grammar as always) It says Gregory is one of the kids, and since the other three are mentioned in the next sentence, he must be the 4th one.
- If there are 1000 pages, and one tells the truth, consequently 999 pages are lying. And that is what page 999 says.
- The tricky part here is how the books are placed. The riddle assumes they are placed as 1-2-3. this means that the bookworm starts at page 1, vol 1, will eat its way through the cover of vol 1, the whole vol 2, the back cover of vol 1 and then stop at the last page of vol 3. That’s 2 covers and 1 whole book, which gives 2*0.25+2.5=3.
- 15 lions that haven’t eaten for 5 years would be very hungry if it wasn’t for the fact that they are dead.
- Since his father was dead, the doctor who said “He is my son” must be his mother. This riddle seems bit out of place, since the whole story is meant to describe some sort of almost ancient civilization. :p
- The killer is the maid, with the motivation that there’s no mail in Sundays. Well, there are probably a lot of countries there is mail delivery in Sundays. They probably picked this one from a Sherlock Holmes book or something.
- The letter m appears once in the word minute, twice in moment but nowhere in the word years.
- This message:
Uif cfhjoojoh pg fufsojuz
uif foe pg ujnf boe tqbdf
uif cfhjoojoh pg fwfsz foe,
Boe uif foe pg fwfsz qm qmbdf.
is coded with a simple caesar cipher (Rot1) “Page -1″ also gives a clue about this. By shifting every letter one step to the left you get:
The beginning of eternity
The end of time and space
The beginning of every end,
And the end of every place.
Again, they’re looking for a letter, namely e, since eternity begins with e etc.
However, I don’t get the point of the left sheet, “P, page +3″ Shifting P with +3 gives S, which is no help. Maybe they’re referring to the answer to the previous question, (M shift +3 = P)
- Classic combinatorial style question. There are 6 pairs of black boots and 6 pairs of brown boots. If you pick 12 boots and have maximum bad luck, you’ll get 6 brown lefts and 6 black lefts. But at that point if you pick another shoe, it is guranteed to be either a black or brown right shoe. In other words, 13 is the lowest number of boots you need to pick to be guaranteed to get a mathing pair.
- The snail effectively climbs one foot a day. On day 27 it climbs up from 26 feet to 29 feet, but slips back to 27 feet. But on day 28, it climbs from 27 feet to 30 feet, and doesn’t need two more days to reach the top.
- Captain obvious says: Before Everest was discovered, Everest was still the tallest mountain. Yet another riddle that’s a bit out of context for the story.
- Let’s read the story backwards.Assume August left with as little as possible:
August took 1 fish, (A third) and left 2. (Two thirds) Before that, he threw away 1 fish.
In other words, there were 4 fish when he arrived at fishplace.
So, June left 4 fish, (Two thirds) and took 2. (One third) Before that, he threw away 1 fish.
In other words, there were 7 fish when he arrived at fishplace.
So, April left 7 fish, (Two thirds) … But since 7 is not divisible by 2, the assumption was wrong, let’s start allover.
Same error happens if we start out with takes 2, leaves 4.
August took 3 fish, (A third) and left 6. (Two thirds) Before that, he threw away 1 fish.
In other words, there were 10 fish when he arrived at fishplace.
So, June left 10 fish, (Two thirds) and took 5. (One third) Before that, he threw away 1 fish.
In other words, there were 16 fish when he arrived at fishplace.
So, April left 16 fish, (Two thirds) and took 8. (One third) Before that, he threw away 1 fish.
In other words, there were 25 fish when he arrived at fishplace.
Which is the answer they expect. However, that answer is not unique. In fact any value given by the function:
f(i)=27*i-2 [Where i>0 and is an integer]
is a valid number of fish to start out with. (25, 52, 79, 106…) However, they only accept 25 as an answer. They could’ve avoided this ambiguity by defining the number fo fish that were left when all three brothers were done. But they didn’t.
- Let’s build a truth table where Gregory, April, August and June are represented by the letter A-D (And their actions by the letter a-d, so a means “Gergory broke the window” for example) I’m using a C-style notation, so, ! means not.
A B C D 1st time !a !b b b 2nd time d !c !b !d
We now have two useful rules here: Two people told the truth and two people lied. We have a depency here: if D tells the truth, so must C; if D lies, so must C. So we have two possible outcomes. Here’s the truth table redrawn for the two outcomes, with things that are true (Áccording to the assumption) marked in bold.
Assumption 1 A B C D 1st time !a !b b b 2nd time d !c !b !d Assumption 2 A B C D 1st time !a !b b b 2nd time d !c !b !d
In assumption A, we get a lot of contradictions, following the statement, both A, B and D would be guilty. On the other hand, in assumption B we get a sound result: A, B and D are innocent, and C is guilty. (C=August)
- This one requires some mathematical reasoning. The sum of every row is a sum of numbers:
… for row n. Let’s not care about the exact value of those numbers for now, and just think of them as symbols. Instead look at the average value of every row which is
… for row n, since row n contains n elements.
This is something we can use, because we can get the average for every row easily. the average for every row is the middle number (Or the sum of the two middle number if a row contains an odd number of numbers) The averages for the displayed rows are:
Anyone who knows math should recognize these numbers as squares. In other words we can also express the aerage function as:
By setting up the two expressions for the average function as an equation:
For row 20 this is 203=20*20*20=8000
- The problem here is that the triangles overlap. However, you can make the calculation simpler by using the symmetry, by choosing a section and counting the triangles in that section and multiplying by 5. The number of subtriangles is 7, so the total number of triangles is 5*7=35.
Here’s a possibly annoying GIF animation showing the 7 subtriangles.
- The flood will double its size every day. So if half the city is flooded after 59 days, obviously if you double that, the whole city will be flooded after 60 days.
Update: Thanks to this page there are OVER 9000 people on the “list of the people who have proved their logic”. (Don’t blame me. They are the ones who don’t know the difference between proven and proved, not me)
Raspunsuri la proveyourlogic. Raspunsuri la proveryourlogic. Raspunsuri la powerlogic.