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My doubt is just a confusion in the permutation combination how do we calculate for items not together .. what is the difference between using the way that
we make them together and subtract them from the arrangement of all (method 1).. or
multiplying by for eg we have 9 places and 4 items should not be together so 9P4 ?! (method 2)
.. why sometimes I get this wrong !!
for example here we use (method 2) in Q6 (iii)
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s13_qp_62.pdf
and here we use (method 1) in Q7 (iii)
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s13_qp_63.pdf
So can someone "Please" Explain what is the difference between this 2 methods and when to use each method .. thanks in Advance !!
we make them together and subtract them from the arrangement of all (method 1).. or
multiplying by for eg we have 9 places and 4 items should not be together so 9P4 ?! (method 2)
.. why sometimes I get this wrong !!
for example here we use (method 2) in Q6 (iii)
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s13_qp_62.pdf
and here we use (method 1) in Q7 (iii)
http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s13_qp_63.pdf
So can someone "Please" Explain what is the difference between this 2 methods and when to use each method .. thanks in Advance !!