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Word problems: Sum to n terms of an arithmetic progression

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Problem

It took Samia 20 minutes to write a 2,300 word essay. She typed 20 words in the first minute. She increased the number of words by a constant, c, every minute.
Find c.
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi