Add new comment

Want facts and want them fast? Our Maths in a minute series explores key mathematical concepts in just a few words.
We talk to Stuart Johnston who uses mathematics to find out how noise pollution in the oceans impacts whales.
Generating electricity without the use of fossil fuels is not just an engineering and industrial challenge, it is also a huge mathematical challenge.
In this podcast author Coralie Colmez shares insights into her novel The irrational diary of Clara Valentine.
We talk to early career mathematicians who spent some of their summer holiday solving problems posed by industry — such as how to blend a perfect smoothie!
Don't like plantbased meat alternatives, but want to spare animals and the environment? There's hope on the horizon, aided by a good helping of maths.
If x and 2x are the amounts in the envelopes, then the expected value at the beginning of the game is (3/2)x.
You choose an envelope.
If you switch envelopes, the expected value of the money in the envelope you switch to is STILL (3/2)x.
The error is that when you say "switching can double your money to 2x or halve it to x/2", you are making a tacit assumption that you have information about your current choice  that you know what x itself is in some sense. This isn't the Monty Hall problem at all  in the MH problem you've gained information before you are offered the option of changing doors. Here, you've gained NO information in between, so there's no advantage to switching.