The number of different words that can be made from the letters of the word INTERMEDIATE, such that two vowels never come together, is __________.
Number of letters in INTERMEDIATE is 12.
Number of vowels $(A, E, E, I, I, E)$ i.e is 6 .
Number of consonants (T T . R M N D) i.e is $6 .$
$\therefore$ Total words are $\frac{12 !}{3 ! 2 ! 2 !}$
Now, number of ways of arranging 6 consonants (2 alike) is
$\frac{6 !}{2 !}=6 \times 5 \times 4 \times 3$
= 360
There are 7 gaps in which 6 vowels can be arranged in 7P6 ways but 2 are alike of are kind and 3 of other kind
$\therefore$ Number of ways of arranging the vowels is ${ }^{7} P_{6} \times \frac{1}{3 ! 21}$
$=\frac{7 !}{1 !} \times \frac{1}{3 ! 2 !}$
$=\frac{7 !}{3 \times 2 \times 2}=\frac{7 \times 6 \times 5 \times 4 \times 3 \times 2 \times 1}{3 \times 2 \times 2}$
$=20 \times 21$
$=420$
Hence, the total number of ways when the two vowels never come together is
360 × 420
= 151200