Question

Five books on Mathematics and 3 books on Physics are placed at random on a bookshelf. What is the probability that books on Mathematics are placed side by side on the bookshelf.

CLASS 12TH ICSE MATHEMATICS SAMPLE PAPER 2018-19

Answer 1

Let We have B1,B2,B3,.......................,B10B1,B2,B3,.......................,B10books.

Then Total no. of arrangement of 1010 Diff. books in a row is 10!10!

Now Here we arrange 33 Given book in side by side so we will take 3−3− as a one bundle and remaining other 77 books and arrange the 11 bundle and 77 books in a row

Which is 8!×3!8!×3!(for arranging bundle of 33book)

So probability =8!×3!10!=115=8!×3!10!=115

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Answer 2

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