Question 870638
in how many ways the 3 books of math 2 books of chemistry and 2 books of physics can be placed in a shelf. so that the books of same subject are placed together
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Choose the orderings of the 3 subjects left to right on the shelf in 3! ways
Choose the orderings of the 3 math books left to right in 3! ways.
Choose the orderings of the 2 chemistry books left to right in 2! ways.
Choose the orderings of the 2 physics books left to right in 2! ways.

Answer: 3!3!2!2! = 6·6·2·2 = 144 ways

Edwin</pre>