All the letters of the word 'EAMCET' are arranged in different possible ways.

Question:

All the letters of the word 'EAMCET' are arranged in different possible ways. The number of such arrangements in which two vowels are adjacent to each other, is

(a) 360

(b) 144

(c) 72

(d) 54

Solution:

Total number of words using letters of  EAMCET is

$\frac{6 !}{2}=\frac{6 \times 5 \times 4 \times 3 \times 1}{2}$ (Since $\mathrm{E}$ is respected twice)

= 360

Total number of words with no two vowels together is :-

Since vowels are $E, A, E=3$ and consonant is $M_{1} C_{1} T=3$.

i.e number of ways to arrange consonant is 3!

– C – C – C –

i.e vowel can take any of 4 places 

i.e number of vowels arrangement $=3 ! \times{ }^{4} P_{3} \times \frac{1}{2}(\because E$ is repeated twice $)$

i.e $3 ! \times \frac{4 !}{1 !} \times \frac{1}{2}=72$

$\therefore$ Number of words arrangement so that two vowels are adjacent $=\frac{360-72}{2}=144$

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Soham
Nov. 10, 2022, 8:11 a.m.
why divided by 2
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