QJEEM20Maf024: JEE Main 2020 Mathematics - Class 11 JEEM20Maf024 Solution: The number of 4 letter words (with or without meaning) that can …

2A, 2I, 2N, E, X, M, T, O

To form four letter words

Case 1 : All same ( not possible)

Case 2 : 1 different, 3 same (not possible)

Case 3 : 2 different, 2 same

= ³C₁ $$\times$$ ⁷C₂ $$\times$$ $$\frac{4!}{2!}$$ = 756

Case 4 : 2 same of one kind, 2 same same of other kind

= ³C₂ $$\times$$ $$\frac{4!}{2!2!}$$ = 18

Case 5 : All letters are different

= ⁸C₄ $$\times$$ 4! = 1680

$$\therefore$$ Total ways = 1680 + 756 + 18 = 2454