On 05/06/2015 15:01, Tim Watts wrote:
GCSE's getting harder causes Paul Dacre's head to explode.

or

"Slightly hard" GCSE Maths Question causes outrage...


http://www.bbc.co.uk/news/education-33017299



The actual question was:

Hannah has 6 orange sweets and some yellow sweets.
Overall, she has n sweets.
The probability of her taking 2 orange sweets is 1/3.

Prove that: n^2-n-90=0

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It's quadratic - and it factorises.

n^2-n-90=0

(n+9)(n-10) = 0

so n = 10

1st selection: = 6/10 probability of selecting an orange sweet (there
are 10 sweets overall, and 6 of them are orange)

2nd selection: = 5/9 probability of selecting an orange sweet (there are
now 9 sweets remaining and 5 of them are orange.

overall probability = 6/10 x 5/9 = 30/90 -- 1/3