How many distinct arrangements can be made from the letters of “BANKING”? (N appears twice; other letters are distinct.)
Aptitude
Permutation and Combination
Difficulty: Easy
Choose an option
-
A5040
-
B2540
-
C5080
-
D2520
Answer
Correct Answer: 2520
Explanation
Introduction / Context:To count permutations of a word with repeated letters, divide n! by factorials of multiplicities. “BANKING” has 7 letters with N repeated twice.
Given Data / Assumptions:
- Total letters = 7; multiplicity: N × 2.
Concept / Approach:Compute 7! / 2!.
Step-by-Step Solution:
7! / 2! = 5040 / 2 = 2520.Verification / Alternative check:Listing patterns confirms that exchanging the two N’s does not produce a new arrangement, hence the 2! divisor.
Why Other Options Are Wrong:5040 ignores repetition; 2540 and 5080 are not valid factorial-based counts.
Common Pitfalls:Overlooking exact multiplicities or dividing by the wrong factor.
Final Answer:2520