JEE Main & Advanced
Mathematics
Permutations and Combinations
Question Bank
Definition of permutation, Number of permutations with or without repetition, Conditional permutations
question_answer
How many numbers consisting of 5 digits can be formed in which the digits 3, 4 and 7 are used only once and the digit 5 is used twice
A)30
B)60
C)45
D)90
Correct Answer:
B
Solution :
Required number of ways are \[\frac{5\,!}{2\,!}=60\].