Question

On a shelf there are 4 books on economics 3 books of mathematics and 4 books of statistics.in how many different ways,can the book be arranged so that the books of economics are kept together?

Answer 1

Number of ways to order the 4 economics books = 4! = 24.

Now fix the order of the economics books. So we can treat the 4 economics books as one single book in what follows. So we work with a total of 8 books now.

For each arrangement of the economics books,

number of arrangements of all books = 8! =40320.

Hence total possible arrangements = 24 x 40320 = 967680.