i was told that in the Probability and Logic subforum
i can ask question like this one:
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mary bought ten books
5 pairs of books
each pair of books has its own colors
a yellow pair ,a purple pair ,a black pair ,a blue pair, a red pair (10 books )
she decided to arrange them on 4 shelves ,but there are rules for arranging them
two books of the same color will not be on the same shelf
a yellow book cannot be on the same shelf with a purple shelf
a blue book will always be with a red book
in each shelf the amount of books will not exceed 3 books
what arrangement cannot happen if we know that on one self we have a purple and a blue books?
A.there is another shelf which has a purple and a blue book on it
B.there is a black book next to a red book
C.there is a yellow book next to a black book
D.there is a purple book next to a black book
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is it here??