First slide
Permutations
Question

The 11 number of arrangements that can be made with the letters of the word 'MATHEMATICS' in which all vowels come together, is

Moderate
Solution

There are 4 vowels viz. A, E, A, I. Considering these four vowels as one letter we have 8 letters (M, T, H, M, T .. C, S and one letter obtained by combining all vowels), out or which M occurs twice, T occurs twice and the rest all different. These 8 letters can be arranged in 8!2!×2! ways.

But, the four vowels (A, E, A, I) can be put together in 4!2! ways.

Hence, the total number of arrangements in which vowels are alwavs together =8!2!×2!×4!2!.

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