Given, word Probability Number of letter in probability P,R,O,A,L,T,Y,BB,II (i) 4 letter are selected alone different i.e. ‌9C4=‌
9!
4!5!
=126 (ii) Two letter or alike other are different 2C1×8C2=‌
2×8!
2!6!
=56 (iii) Two letter are alike 2C2=1 Total number of sample space =126+56+1=183 Favorable case in which at least one letter is repeated ‌ i.e., ‌‌‌56+1=57 ∴‌‌ Reqmend probability =‌