Class 11MathematicsPermutation and CombinationDefinition of permutation, Number of permutations with or without repetition, Conditional permutations
EasyIf $^n{P_r} = 720 \times {^n{C_r}}$,then $r$ is equal to:
- A$6$
- B$5$
- C$4$
- D$7$
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Similar Questions
In how many of the distinct permutations of the letters in $MISSISSIPPI$ do the four $I$'s not come together?
Difficult
View SolutionHow many numbers can be formed using the digits $0, 1, 2, 3, 4, 5$ that are greater than $3000$ (repetition is not allowed)?
MediumIIT 1976
View SolutionThe number of words formed from the letters of the word $RAJASTHAN$ by taking all the letters at a time in which vowels are alternate is:
The number of ways to form a $7$-digit number using the digits $1, 2, 3, 4, 3, 2, 1$ such that odd digits always occupy odd places is:
The number of five-digit numbers divisible by $5$ that can be formed using the digits $0, 1, 2, 3, 4, 5$ without repetition is
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