This GMAT quant practice question is a classic permutation question. Concept tested: Reordering 'n' distinct elements. A GMAT 600 level, easy problem solving sample question.
Question 8: In how many ways can the letters of the word "PROBLEM" be rearranged to make 7 letter words such that none of the letters repeat?
The letters of the word PROBLEM are distinct.
There are seven positions to be filled to form 7 letter words using the letters in the word PROBLEM.
The first position can be filled using any of the 7 letters contained in PROBLEM.
The second position can be filled by the remaining 6 letters as the letters should not repeat.
The third position can be filled by the remaining 5 letters and so on.
Therefore, the total number of ways of forming 7 letter words
= 7 × 6 × 5 × 4 × 3 × 2 × 1 = 7! ways.
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