How many different selections of 4 books can be made from 10 different books, if
(i)there is no restriction?
(ii)two particular books are always selected?
(iii)two particular books are never selected?

contexto.140

3 years ago

Answer : Since there are 10 different books out of which 4 is to be selected .

No. of ways in which 4 books be selected = ¹⁰C4

= 210 ways

Since two particular books are always selected, so ways of selecting 2 books from 8 are

= ⁸C2 ways

= 28 ways

Since two particular books are never selected so, ways of selecting 4 books from 8 are

= ⁸C4 ways

= 70 ways