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permutation problem .?
--find the number of arrangements of letters for the word 'RADAR'--
This is what I did:
5! / (2! 2! 5!)
I think I did the bottom part wrong. the 2! are for the letters A and R. is 5 the right factorial number for d?
2 Answers
- 1 decade agoFavorite Answer
the 5! on bottom should be a 1!, the numbers on bottom count repetitions of the letters, so your 2s are correct.
- Anonymous1 decade ago
Choose two spots for the R's, C(5,2)
Choose two spots for the A's from those remaining, C(3,2)
Choose the remaining spot for the D, C(1,1)
and multiply these together.
I Think its C(5,2)*C(3,2)*C(1,1)