A test question that stumped many students!

A version of this problem was asked in India. Can you figure it out?

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[chinareds]

"A physicist, a biologist and a mathematician are sitting in a street cafe watching people entering and leaving the house on the other side of the street. First they see two people entering the house. Time passes. After a while they notice three people leaving the house. The physicist says, "The measurement wasn't accurate." The biologist says, "They must have reproduced." The mathematician says, "If one more person enters the house then it will be empty."

[paulmasterson]

I did this with matrices and was driving myself crazy thinking I could no longer do math with matrices. Nope, just turns out this problem is super troll.

[firelow]

We've been tricked, we've been backstabed and we've been, quite possibly, bamboozled

[roqsteady]

Actually it is easy: “a sack contains 4 different coloured balls”. So there are four balls in the sack… Next.

[Palimbacchius]

He begins by claiming that the sack contains four balls of different colours (NOT balls of four different colours). Precision and clear thinking are important.

[utku]

I found it 22 and then said “ no it can’t be Third is -2, I must have done something wrong” for at least 15 minutes then look up the answer and realized I wasted 15 minutes trying to correct something that’s already correct.

[Hangrid]

My trust in you is such that you got me thinking i wasn't as good at math as i thought...never thought nonsense was a answer.

[Volti]

I was literally doing it for 2 hours, finding why it was equal to -2 and where was my mistake. It was actually right. Great.

[Purpylon]

By the way, the problem says "a sack contains 4 different colored balls", thus limiting the problem to only 4 balls, all of different color.

[googletaqiyya]

"A sack contains *FOUR* different colored balls. How many balls are in the sack?" Hint: a whole number between 3 and 5.
A sack contains an unknown number of balls, of which have 4 differing colors. How many....

[LynnXternal]

"A sack contains balls of four different colors" is a lot clearer than the wording in the question

edit - I can't reply to my own comment; youtube keeps removing them as soon as i post them

[HansPeter-qgvc]

Yeah, I totally didn't spend the past 10 minutes thinking I wasn't able to do simple arithmetic anymore.

[GRAHAMAUS]

"A sack contains 4 (different coloured) balls. How many balls are there?". Errr, 4. The problem here is not maths, it's English. The question should be "A sack contains a number of balls, of 4 different colours..."

[markt]

You know, when a question has no answer, it's not surprising that students, who ordinarily expect that problems they are being given will have answers that can be derived from the knowledge they acquired in class, would not be easily able to solve it. A student may very well easily perform all of the calculations in the video, but upon seeing that the answer they arrived at was nonsensical, they would be more likely to doubt their calculations and their method than they would be to conclude that the question was not intended to have an answer, and in a time-limited situation such as a test, they might just give up on it and move on to other problems.

Reasonably, if a teacher is going to give students an unsolvable problem in a test, I think they should at least provide an example of one either in-class or else one of many different questions in a regular homework assignment that they will get feedback from before the test, so that they can learn how to recognize situations where it happens.

[TheLobsterCopter]

I worked it out a different way:

Since 24 balls are not red, there are at least 24 balls.
If 12 balls are not pink, at least 24-12=12 balls must be pink
If 14 balls are not blue, at least 24-14=10 balls must be blue
If 16 balls are not yellow, at least 24-16=8 balls must be yellow
At least 12+10+8=30 balls are either pink, blue or yellow, i.e not red. This is a contradiction, therefore the information given cannot be correct.

[kiwininja]

I first saw the question as "there are four colored balls" which led to me to believe the answer was 4 😂

[celestiallia]

I solved this within 2 minutes and assumed there must be a mistake because I didn’t get a solution, so I tried to figure out where I went wrong… that time was not well spent…

[jdnoflegend]

the difference between a teacher & a student is the confidence u have in your own answers

[richdibo]

Hopefully, there is some pedantic value to abusing students in this manner.

[kelleysimonds]

What if the sack contains 24 ball and 6 balls are magenta, 6 are green, 6 are lavender and, 6 are orange. This meets all of that stated conditions.