LONDON -- It's a math question that has provoked outrage, confused people on Twitter and even prompted thousands of students to sign a petition asking for the chance to resit the entire exam -- so think can you figure out the probability riddle that's perplexed so many British pupils?
The tricky question appeared on Thursday on the GCSE exam, which is taken by students in secondary schools in the UK around ages 15 or 16. It's a compulsory exam, so about 500,000 took the test.
Phones were not allowed during the test, acording to a representative from the Office of Qualifications and Examinations Regulation (Ofqual), so it's unclear how the exam paper could have been photographed. However, there's nothing to stop someone from writing down the question and taking it home.
Here's the question on the test, which was set by the British education and examination board Edexcel
There are n sweets in a bag. Six of the sweets are orange. The rest of the sweets are yellow. Hannah takes a random sweet from the bag. She eats the sweet. Hannah then takes at random another sweet from the bag. She eats the sweet. The probability that Hannah eats two orange sweets is 1/3. Show that n²-n-90=0.
Professor Ian Dryden, the head of mathematical sciences at the University of Nottingham, has solved the problem for Mashable. Here's how he did it:
If you're still scratching your head, this video uploaded to YouTube goes through the whole process.
There was a lot of outrage on Twitter from teachers and students alike using the hashtag #EdexcelMaths.
In 20 yrs of teaching I have never seen a probability tree diagram lead to a quadratic equation. Well played edexcel. #EdexcelMaths #sarcasm— Dave Watkins (@joshfishkins) June 5, 2015
"Hannah's has 6 sweets in her bag prove that n2-n-90=0" #EdexcelMaths pic.twitter.com/nyai7rukFV— Gail (@AbigayleWils0n) June 4, 2015
When 25 year olds on twitter are telling everyone how they solved Hannah's sweets in under four minutes #EdexcelMaths pic.twitter.com/RRnV0cGTyf— baesut (@junglejim_4322) June 5, 2015
What #EdexcelMaths were thinking whilst making our exam paper pic.twitter.com/9Vg4g0qXKW— (@MollyRoberts33) June 5, 2015
First half of the paper compared to the second half #EdexcelMaths pic.twitter.com/ljqhwgaPWS— Chad (@Jxgielka) June 4, 2015
Hannah ate a sweet so now tell me how n2 - n - 90 = 0 #EdexcelMaths http://t.co/YwXC0kMZUp— Ash (@VavaZouma) June 4, 2015
Doing the first half of the paper and then reaching the second half #EdexcelMaths pic.twitter.com/alZBoqAUEe— Fern Semple (@ageofpizza) June 4, 2015
"Show that n²-n-90=0" #EdexcelMaths pic.twitter.com/pnbAgsysfa— liv (@helloiamliv) June 4, 2015
Others were just looking to the future, hoping for a better day.
Fingers crossed for me and half of England that the calculator paper actually makes sense #EdexcelMaths— Milly keith (@KeithMilly) June 5, 2015