The number of words from the letters of the words HARAHUA in which R and U will never come together ...........

Quantitative Aptitude (CDS) Permutation & Combination

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The number of words from the letters of the words HARAHUA in which R and U will never come together, is?

630

360

350

None of these

Explanation:

HARAHUA
There are 7 letters in the word HARAHUA, in which two H’s and three A’s are identical.
Hence the total number of words with these letters
= 7! / 2! 3!
= 7×6×5×4/2 = 420
Also the number of words in which R and U come together
= 6! /2! 3!
= 6×5×4 / 2 = 60
Therefore, the required number of words
= 420 – 60
= 360