You have 30 seconds. Viral riddle from The 1% Club

[@Jerry_Fried]

I think the most efficient way to think about it is not in terms of 99% vs 98%. It is in terms 1% vs 2%. One person equals one percent of one hundred people. The same one person equals two percent of how many people? 50. So 50 people have to leave.

[@mdmishfaqahmed2138]

Now, how many to make it 97% 🙄

[@Danimal.69]

1 / (1 + 1) = 50% 1 / (1 + 2) = 33% 1 / (1 + 9) = 10% 1 / (1 + 19) = 5% 1 / (1 + 49 ) = 2%

[@briant7265]

My approach was: 1? Nope. Brief thought. 50? Yup. Going back to do it analytically, I did what you did: 1% = 1/100 2% = 1/50 Done.

[@tedn6855]

Not a round number at least 67 would have to leave for 3%

[@pileb]

Yeah, focus on remaining items, not on leaving ones 🙂

[@aliasmask]

The way I thought of it is the 1 right hander has to be 2% of the room, so total needs to be 50, so 50 left handers need to leave.

[@ompattewar3493]

This is how I got it too. Pretty straight forward.

[@GodmanchesterGoblin]

Yes, by considering that 1 person is 2% I got the correct answer in less than ten seconds. Maybe I should start entering game shows...

[@HpPmL]

Did you just assume that person's laterality?

[@Hasinoyomoy]

Yeah, it was pretty easy tbh

[@MichaelSmith-fj7di]

The answer is that 50 people must leave. We know that 49/50 is equal to 98%, thus, since there are 99 people who are left-handed currently and you need 49, 50 must leave.

[@youtubeuser1052]

Yep, it should be instantly obvious that 98/100 = 49/50 based on the obvious fact that if the numerator and denominator are both even you can reduce any fraction by dividing by two. Once you notice that, you just need the obvious fact that 99/100 left handed people means one right handed person, and therefore you just need to go from 99 left handed to 49 left handed in the room to get to the target 49/50.

[@Stirdix]

Intuitively, it's like trying to increase the saltiness of saltwater by removing water rather than by adding salt. Since most of saltwater is water, you have to boil off a lot of water vs. adding a small amount of salt to change the concentration.

[@iWizardzZ_x]

Flip it, in a room of 100 people, 1% are right handed so only 1 person. To raise that to 2% 50 people must leave.

[@mihirdhakan7042]

Yep this is the best one, classic GMAT stuff kudos brother

[@HpPmL]

It never says that the non-left-handed person is right handed. You're making assumptions. They could be missing both arms or identify as ambidextrous or laterality fluid.

[@daakudaddy5453]

You should have continued the graph till 99 left-handed people (Ls) left the room. While the percentage initially drops slowly from 99% to 98%, the decline sharpens till we reach 98 Ls leaving (at which point its 50% with 1 L and 1 Rleft in the room), and then drops very sharply to 0% as the last L leaves. It's kind of like the inverse of radioactive decay.

[@glo-tech7124]

Real logic on very last Thats how indians solve mathmatical problems in seconds by applying reasoning Proud on new govt. employees

[@PoppySuzumi1223]

It should be easily seen that 49/50 = 98% So, in order to get 98%, 100-50=50 people must left, so that the remaining one is not left-handed still remains in the room. Quite a logical IQ puzzle.

[@n0dr0gs49]

There is one right handed person (1% of 100) which is 2% of 50.

[@albertjosefsson7304]

Yes, that person not left-handed represents a 1%, in order for that person to represent a 2%, it means his "weight" has to double. Therefore all the rest must half. It is pretty obvious but at first I didn't realized 😮

[@mdmishfaqahmed2138]

Now you know why getting 1 percentile higher becomes so tougher and tougher as you climb higher 🙄

[@Orrinn123]

In 30 seconds 49/50 might as well be a random number. The solution other people posted is much better imo. Which is to think out of how many people does 1 right-handed person make 2%?

[@AdamRapW]

This question is way too sinister to be believable.

[@marvhollingworth663]

You're correct, it should say that most people are right-handed.

[@RainbowDashShadesOfApproval]

You win the comment of the day. This one was out of the left field.

[@davidblack9071]

If you asked me if you missed one question on a 100 point test and got a 99% how many questions would there have to be to miss one question and get a 98% I would have immediately got this in less than 30 seconds. I wonder why my brain failed like this.

[@savageraccoon787]

I got the riddle but putting it in this format makes it surprisingly so much easier

[@smylesg]

There are always one more person in one room than the number of left handers. That makes x/(x+1)=0.98 => x=49. So 50 of the 99 left handers must leave to get down to 49.

[@robheale9860]

Interestingly if 90 lefthanded people leave the room, the percentage of lefthanded people remaining is still 90%

[@ingiford175]

Depends, if you are an engineer and want 98 point something, then 1 should be enough, if you want exactly 98, then 50....

[@GodmanchesterGoblin]

But this engineer would want the percentage to be less than 98.5%, otherwise it's still pretty much the same as 99%. 😊 One leaving would not be enough, but 34 leaving would be.

[@daveincognito]

98% of the room needs to be left-handed. You have 1 person who is (presumably) right handed. 1 is 2 percent of what number?

[@mikoaj1349]

I did solve this in under 30 seconds with no problem, but I had access to pen and paper. I don't know if they have those on the show and I doubt I'd be able to calculate this in memory, and under time pressure to boot.

[@tuomasronnberg5244]

This is trivial to solve in your head (if you halve 100 to 50 then you've doubled the 1% to 2%). Many people in the comments have reported solving it in under 10 seconds.

[@r6u356une56ney]

Damn, I saw the question in the thumbnail, and solved it in less than the time limit before I even clicked the video. Where's my cash?

[@nogard8541]

The way I thought it through in my head was by expressing 98% in terms of 98/100. That simplifies to 49/50. You can quickly do other specific calculations that way too. 90% is 90/100 which reduces to 9/10. 75% is 75/100 which reduces to 3/4, etc... As long as the denominator is exactly one greater than the numerator, you can have a valid percentage to aim for.

[@fiathla]

It's just me, or these videos are becoming easier with the years?

[@PhonyHomie86]

There can be a 100 people in a room and 99 don’t believe in you…

[@deerh2o]

In general, most math contest folks know that only the factors of 100 lead to an integer percentage (between 1 and 100). So if x is a factor of 100, 1/x is an integer percentage. The two highest factors of 100 are 50 and 100, leading to 2% and 1%. Focusing on the left-handers gives the puzzle it's juice, but focusing on the single right-hander leads to the quick and elegant solution.

[@andymanaus1077]

I thought of the question in terms of the frequency of the non left handed person. 1% is equivalent to a frequency of 1 in 100. 2% is equivalent to a frequency of 1 in 50. Therefore to accomplish a state where 98% of people are left handed, 49 left handed people must be in the room. 99 - 49 = 50

[@mathmannix]

Thanks, watermelon puzzle!

[@D1g1talMess]

98% = 98/100 simplifying the fraction brings it to 49/50 admittedly, I didn't know the answer at first, but after it was revealed, it seemed obvious

[@spence524]

The goal is 98% lefties and the number of righties is constant at 1. If we want to know about 98% lefties, that means 2% right handers. If we say X equals the total population of people then the simple equation is 1/X = 2/100. Cross multiply and solve for X. 2X = 100. X= 50. Pencil drop.

[@kiritokun7474]

it could be difficult to think smart live in a TV Show with a time limit.. but to see this "problem" in a chill situation makes it not even hard.. it is maybe only surprising for ppl who not think much about percentages.. i do it often for fun or to calculate win/loss in my fav video game.. maybe thats why it was not such of a problem for me or even surprising 🤔

[@wiggles7976]

If there is 1ppm fluoride in the water, you gotta remove a LOT of water (removing just water, not fluoride) to up the concentration, supposing you had a litre of solution. Even removing half the water still doesn't make it very fluoridated by ratio.

[@stevemichael8458]

I don't understand what is paradoxical about this. The right hander needs to be double the percentage so the total number needs to be halved. What paradox?

[@iridiam]

One way I like to think of it is "how many left-handers will need to stop being left-handed to get to 98%?" Obviously, that's 1, since that will give us 98 left-handers and 2 non-left-handers. Now just divide the room into 2 equally sized halves, and the solution is evident.

[@quakerblacksmith1818]

This problem is encountered in the real world too. Oil filters have a beta rating indicating how efficiently they remove particles of a given size. To calculate the efficiency, you subtract one from the beta rating and divide it by the beta rating (beta-1/beta), so a beta 50 is 98% efficient and a beta 100 is 99% efficient.

[@lagautmd]

Definitely, the folks looking at it as increasing from 1 to 2% are identifying the quickest accurate way to get it. I thought about it as an iterative search via an analogy of Newton's method with my intuition pointing towards something like 10 to 25 leaving the room. And, the mental math should be quick: 0% are left handers when 99 have left the room. So, the midpoint is about 50, let's look there, and that's the answer. But, that was just a happy coincidence. I was prepared for it to be too low again and needing to go to 25 leaving and finding that ratio might be too high or low and needing to either have more or less than 25 leave. .

[@paparmar]

Given that we are dealing with exclusively whole numbers, the only possible way to have a group of under 100 people that has a subgroup that is exactly 98% of the total is 49/50. So you'd need 50 lefties to leave. In other words, if you tell me you scored 98% on a test that had less than 100 questions, I'd know you must have gotten 49/50 (OK - assuming each question was worth either zero or 1 pt., analogous to each person being either right or left handed).

[@SumitKumar-oz7th]

(99-x)/(100-x)=98/100 X=50

[@johngregory8576]

50 lefties have to leave. 1 right (1/100=1%)+ 99 left (99/100=99%) => 1 right (1/50=2%) and 49 left (49/50=98%)

[@ZytJans]

98% is exactly 49/50. Thus, 50 left handed people should leave to reach 98%.

[@maxhagenauer24]

Black Pen Red Pen did this exact problem a few days ago. (99 - x) / (100 - x) = 0.98, x = 50

[@YDS8479]

i love all these maths puzzles

[@ATHIP12]

I immediately wondered if the question allowed us to round down. If that's the case, we need 34 people to leave to get it to 66/65 or 98.48%.

[@RavenMobile]

Haven't watched the video yet, but I came up with 50 in about 5 seconds. I think my math is right. Take away 1 person and you have 1/99 right-handed. To get that to 98% it needs to be 1/50, so take away 50 lefties.

[@qekruxt5089]

solving a puzzle faster than someone else doesn't mean you have the higher IQ, fyi

[@terry_willis]

I saw this same riddle several days ago. It must be making the rounds.

[@yikaiye9241]

if you want something to double its share without changing the number of that thing, cut the total by half.

[@44daggers44]

The right hander is 1% of the room. To double his percentage value, you have to halve the room.

[@Shadozcreeping]

50. 99 out of 100 is 99% 49 out of 50 is 98%, so half of the people in the room need to leave before the right handed individual could constitute 2% of the room's population

[@wiggles7976]

We have 1 right handed person, 99 left-handed. We need 98/100 people left handed, or 49/50 people left handed, so if 50 left-handed people leave, we have 49 left-handed, and 1 right-handed, achieving the required ratio.

[@Frank-kq4te]

Think the other way around , 1/100 is righthanded, so 1%. In order to duble the percentage, you need to half the quantity, because 1/50 is 2%. So if you remove 50 lefthanders, then 1 righthanded among 50 people will be a 2%. That leaves a 98% of lefthanded people in the room.

[@palpytine]

Flip it. There's 1% of right handed people, you need to DOUBLE that percentage, which means halving the number of people who aren't right-handed.

[@Dexaan]

I've seen this one before, probably either here or Numberphile. The trick is indeed to flip the question to focus on the right-handed person (the left-handers are sinister anyway) - how many people need to be in the room to make them 2%? 50.

[@HpPmL]

Where does it say someone is right handed ? Did you just assume this person's laterality ? This person could identify as an ambidextrous or a non-armed person.

[@koalaman18]

I think, given the intelligence and common sense required to get to the 97,000-pound question in the first place, the biggest challenge with this question is the time limit. 30 seconds *should* be enough to think through the problem and solve it, but it feels like a short time and may cause people to panic and give their first instinct of "1 person must leave the room" as their answer. I'd forgotten about the watermelon video and my first thought was that the answer would be close to 1 but likely not a whole number, since that would be unlikely to give exactly 98%. It was only when I paused to check, and realised that 98 out of 99 wasn't even close to 98%, that I corrected myself and realised the correct answer must be 50. I think many people would come to this conclusion, but only too late, after having given the incorrect answer under time pressure.

[@averageboulderer]

50. <a href="#" class="seekto" data-time="2941">49:1</a> makes exactly 98% lefties. Anything over 49 lefties make it 98+some change.

[@JDrapic]

Pre-video solving, another way to think of it is "what is 1 2% of?". You need to reduce the total to 50, so 50 left-handers should leave.

[@BKNeifert]

I figured it out, but only as you explained the problem. It's 50. 49/50. 98/100 reduces to 49/50

[@krzysztofmazurkiewicz5270]

There was a simmilar question with something that weighted 100kg and 99% was water, And the question was how much water needs to go to have this thing contain 98% of water. So as long as one remembers the math its a quick one ;) Edit: yes it was the 100kg potato riddle ;)

[@nitailevi8001]

Solved it, but took longer than 30 seconds. I didn't measure but probably close to a minute. Under pressure in a live show it can be a lot more difficult.

[@Prs722]

My brain has always seen math differently. I never used a formula to go back and forth between a decimal and a percentage. I also always saw fractions as being the same as decimals. Converting between the three, I instantly see 1/50 as 2%. My brain sees that one can simplify 2/100 to 1/50 and that they are equal.

[@donhartfield]

It's not paradoxical. Its recursive because the total number in the room shrinks at the same rate as the number being measured are, leaving only a tiny fraction of change.

[@pklimbic]

One person represents one percent of 100. Of what number (of persons ) does the one person represent 2%? If you ask it like this, you have it in 10 seconds.

[@godsakezz]

98% means 98/100, ie. 49/50. So we have to make 100-50, =50 left-handed leave the room to make 98%.

[@RobG1729]

Think about the percentage of people NOT left-handed. That one person has twice the value, so half the number. Yes, that was what first occured to me.

[@Antoni2602]

30 second time frame to answer and here is this guy explaining it from <a href="#" class="seekto" data-time="84">1:24</a> to <a href="#" class="seekto" data-time="510">8:30</a>, way too long of a thought process :(

[@RavenMobile]

You're wildly overcomplicating your answer with the algebra. All you need to understand is the basics of percentages. 1/100 = 99% 1/? = 98% That is a doubling of the proportion of non-lefties in the room, so we need half as many total people in the room to accomplish that.

[@briant7265]

0 people need to leave, 1 left-handed and -1 right-handed.

[@richardfarrer5616]

The first time I saw this (about potatoes losing a percentage of water), it may have taken me 30 seconds+. But I wish I'd been on the show since it took less than a second this time.

[@chrilaur1143]

Yup…same as the watermelon puzzle. Knew the answer straight away.

[@daakudaddy5453]

I immediately knew that the answer is NOT 1. I think I took more than 30 seconds to arrive at 50. I am tired, sleepy, and in bed. I am also smart, but not too much. So definitely a lot more than 1% of people can solve this in 30 seconds.

[@sbombfitness]

I just guess and checked with a calculator till I got closer and closer to the answer

[@Kounomura]

This problem can be better understood in connection with another, but mathematically identical problem. As Christmas approaches, we give gifts. If I gave gifts to 100 people last year, including myself, at Christmas, but this year I want to give twice as many gifts out of the same amount of money, by how much should I reduce the number of people I give gifts to?

[@Songfugel]

Ugh, it's just 1/100 right handers to 2/100 which is 1/50, so 50 out of 99 left handers has to leave, and that is the answer

[@nicschne]

n/n+1=98/100 so 100n = 98n+98 so 2n= 98, n = 49 so to get from 99 to 49 left handed people 50 must leave

[@verkuilb]

Another answer is that NOBODY needs to leave. You just saw the left arm off of one lefthanded person in the room. That person is now right-handed-meaning that 98 of 100 are lefties, or 98%.

[@RavenMobile]

Just simplify it as "Remove around 1/8th of a leftie (their left arm) and 98% are now right-handed." Beautiful answer! I would award you full points, as it fits all given criteria.

[@martinprince8253]

That's basically the patato water contents riddle but backwards

[@nicholasharvey1232]

This sounds just like the dried fruit problem. Ergo I knew right away the answer was 50.

[@Meshamu]

To be frank, I feel this question would fit in better on "Are You Smarter Than A Fifth Grader?"

[@barneyDcaller]

(99 - x)/(100 - x) = 0.98 99 - x = 0.98 (100 - x) 99 - x = 98 - 0.98x 99 - 98 = x - 0.98x 1 = x - 0.98x 1 = 0.02 x x = 50

[@raileite5994]

God damn, 2 minutes to finally start solving a problem he already solved previously with a different "name"

[@feedbackzaloop]

The real key to all these intellectual games for pseudointellectuals is that questions are typical and somewhat standard. So here one has to remember the problem about 99% dried fruit loosing weight from long ago.

[@porth5165]

1 out of x = 2%, x=50, therefor 50 have to leave

[@evanrosman9226]

50.

[@33LB]

i got the answer to this, but admittedly it was because i am familiar with the potato paradox. i'm not so sure that i would have gotten this if i had to calculate it from scratch in 30 seconds, regardless of mensa membership.

[@jeremiahlyleseditor437]

I've seen this done in college some decades ago. I think the answer was 50 or so.

[@hikari1690]

My gut is telling me 50 but my brain is too sleepy to do the maths for me

[@UncleJoeLITE]

Yep, I just did 0.98 = 49/50. Thanks from Canberra 🇦🇺 Presh.

[@joeschmo622]

Yeah, this was just posted on another channel (thought it was a repeat here at first). Everyone's doing the iterative 99, 98, 97, etc., but I did it from the thumbnail question in like 10sec (if that) by thinking of the 1RH for 99% and 2RH for 98%, so 1/50 vs 1/100, meaning fitty people gots ta go.

[@CharlesReiche]

1 is 2% of what number. 50. Took me about 10 seconds to figure out.

[@marvhollingworth663]

I didn't time how quick I got this but I'm pretty sure it took less than 30 secs. I just thought about the fraction of people that had to be right-handed. It started at 1/100 & had to double to 1/50, which meant 50 people had to leave.

[@igorbatkovich3856]

Blackpenredpen have already researched the problem a few days ago

[@KW-gb9cd]

If 1 person is 2%, then 50 people would be 100%; the answer is 50.

[@brandorrrrgaming1544]

I knew it was 50 in about 10 seconds but it was intuition

[@RyanDouglas-h3d]

2% of X = 1 X = 1/.02 which is 50

[@prithvisinghpanwar007]

Stolen from BPRP

[@NoFutureinLove]

So 100% of the comments solved the puzzle....and THIS is quite amazing...

[@grrman]

What happened to the outro music? I really miss it

[@joaovitormatos8147]

What if the right-handed guy left the room

[@clemente3966]

The last method seems more intuitive that the first one, so I'm wondering why it was not shown first. But then, it was written as 1/2%. Like, why not write it as 1=2% *x, x being the new number of people, then just multiply by 50 in each side, and then do 100-x? Why bother with first thinking about, and so first presenting, the soultion of a curve when the situation was a game show where you have to think in 30 seconds without a tool to generate the curve made by the (99-x)/(100-x) expression? And I'm saying that, because in the version of the show where I'm from, the concept is to have questions that do not require math skills or prior knowledge, just logic, and while that question would still require a bit of math, the 1= 2% *x would be the one with the less math required, even less than 1/2% requiring to bring it back to 100/2 because of the decimal value on the bottom part before getting that it equals 50.

[@Jasminehaydon]

Isn't this the potato paradox just asked in a different way?

[@koits1007]

I like watermelon, only some will get it

[@tannereustace]

I wonder how many people say 49 in accidentally subtracting from 99 instead of 100 despite understanding the logic. Maybe that’s just me?

[@BenjaminYWarner]

That took way more than 30 seconds.

[@TheLucanicLord]

I said 49. Spotted the logic trap, did the arithmetic wrong.

[@isambo400]

Its easy with people but hard with pitato

[@yoav613]

98%=49/50 so 50 need to leave.

[@rayudurayudu9348]

This is mathematically may be correct but logically making no sense because 99% is equal to 100 people 49.5% is equal to 50 people Anyone clarify here