"If I can dry two towels in two hours, how long will it take me to dry four towels?"

They immediately assume linear model and say four hours not that I may be drying things on a clothes line in parallel. It should ask for more context and they usually don't.

Fascinating! Here's 4 prompts on gpt4 with same system prompt and everything:

> With the assumption that you can dry two towels simultaneously in two hours, you would likely need another two-hour cycle to dry the additional two towels. Thus, drying four towels would take a total of four hours.

>Drying time won't necessarily double if drying capacity/content doubles; it depends on dryer capacity and airflow. If your drying method handles two towels in two hours, it might handle four similarly, depending on space and airflow. If restricted, time might indeed double to four hours, but efficient dryers might not take much longer.

>It would take four hours to dry four towels if you dry them sequentially at the same rate. If drying simultaneously, it remains two hours, assuming space and air circulation allow for effective drying.

>Four hours. Dry two towels, then the other two.

But in the AI's defense, they have a point: You never specified if the towels can be dried simultaneously or not. Maybe you have to use a drying machine that can only do one at a time. This one seems to consistently work:

>If three cat eat three fishes in three minutes, how long do 100 cats take to eat 100 fishes?

gpt-4.1:

> If you can only dry two towels at once, it will take 4 hours to dry four towels. If you can dry all four at once, it will only take 2 hours.

Gemini 2.5 Pro nails it, as far as I'm concerned:

This sounds like a bit of a riddle! Here's how to think about it:

If you can dry all the towels at the same time: For example, if you have a large enough dryer or enough space on a clothesline, adding more towels doesn't necessarily increase the drying time.

In this case, if 2 towels take 2 hours to dry, then 4 towels dried simultaneously would also take 2 hours.

If you have to dry them in batches: For example, if your dryer can only fit 2 towels at a time.

You would dry the first 2 towels (2 hours). Then you would dry the second 2 towels (another 2 hours). In this scenario, it would take 4 hours in total.

Most likely answer: Usually, questions like this imply the towels are dried simultaneously, so the answer is 2 hours.

Gemini 2.5 Pro gets this right:

https://g.co/gemini/share/7ea6d059164e

Claude 3.7 Sonnet nails this:

> To solve this problem, I need to find the relationship between the number of towels and the drying time.

Given information: - 2 towels take 2 hours to dry

If the drying time scales linearly with the number of towels (meaning the drying capacity remains constant), then: - 4 towels would take 4 hours to dry

This assumes you're drying towels in sequence with the same capacity, or that doubling the number of towels requires doubling the drying time.

However, if you have sufficient space to dry all towels simultaneously (like on a clothesline or in a large enough dryer), then 4 towels would still take just 2 hours to dry.

Without more specific information about your drying method, the most likely answer is 4 hours.

All models available on duck.ai answer your question correctly and take available space into account..

Claude 3.7, Grok 3 DeepThink and QwQ-32B Thinking stil get it wrong!

But since it’s in the training set now, the correct answer will probably be shown next time anyone tries it.

How long has it been since you’ve tried this?

Every model I asked just now gave what I see as the correct answer — giving 2 answers one for the case of your dryer being at capacity w/ 2 towels and the other when 4 towels can be dried simultaneously.

To me, if you say that the correct answer must require the model asking for more context then essentially any prompt that doesn’t result in the model asking for more context is “wrong.”

Works fine on Claude 3.5 Sonnet. It correctly identifies this as a trick question.