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by Dewie3
4028 days ago
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> Despite the fact that the number of students taking A-level maths has risen in recent years and that girls outperform boys at GCSE, the number of girls taking A-level mathematics is proportionally much lower. Grab the nearest popcorn and watch the gender wars unfold. |
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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.
If a HS student I would imagine you would
First: think of coins p(H1) = .5; p(H2) =.5; p(H1+H2) = .5 * .5 = .25
Second: OK, here (6/n) * (5/(n-1)) = 1/3
Third solve: 30/(n * (n-1)) = 1/3
n=10 or -9; if -9 then Hannah only has one sweet and lifted 9 from somebody else just to demo her point.(from London Telegraph today)