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Maths, Addmaths and Statistics: Post your doubts here!

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http://papers.xtremepapers.com/CIE/Cambridge International O Level/Mathematics D (Calculator Version) (4024)/4024_w06_qp_2.pdf
In the last question, 11, last part , e, why do we need to multiply the probability by two when we're already selecting 2 students only?
There is no order given thus we will multiply by 2.

More clearly
Student higher than 170 = A
Student lower than 140=B

One probability is A x B (A chosen then B) and other is B x A(B chosen then A)Since both are AB we will add their probabilities and it will seem that we have multiplied by 2,while we have just added the 2 orders.
 
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