Question

There are 5 books on Mathematics and 6 books on Physics in a book shop. In how many ways can a students buy : (i) a Mathematics book and a Physics book (ii) either a Mathematics book or a Physics book?

Answer 1

Number of books on mathematics = 5
Number of books on physics = 6
Number of ways of buying a mathematics book = 5
Similarly, number of ways of buying a physics book = 6
(i) By using fundamental principle of multiplication:
Number of ways of buying a mathematics and a physics book = 6$\times$5 = 30
(ii) By using the fundamental principle of addition:
Number of ways of buying either a mathematics or a physics book = 6 + 5 = 11