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Question
Letters in the word HULULULU are rearranged. The probability of all three L being together is ______.
Options
`3/20`
`2/5`
`3/28`
`5/23`
MCQ
Solution
Letters in the word HULULULU are rearranged. The probability of all three L being together is `underlinebb(3/28)`.
Explanation:
The word HULULULU contains 4U, 3L and 1H.
Consider 3L together i.e. we have to arrange 6 units that contains 4U.
Hence number of possible arrangements
= `(6!)/(4!)`
= 6 × 5
= 30
Number of ways of arranging all letters of given word
= `(8!)/(3!4!)`
= `(8 xx 7 xx 6 xx 5)/(3 xx 2)`
= 8 × 7 × 5
Hence required probability
= `30/(8 xx 7 xx 5)`
= `6/(8 xx 7)`
= `3/28`
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Permutations - Permutations When Some Objects Are Identical
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