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Unilorin Post-UTME Mathematics 2015 (Model questions) Question 22

Question 22

Progressions

Find the number of terms in an arithmetic given that the first and last terms are a and 37a respectively and that its common difference is 4a

  1. A.15
  2. B.10
  3. C.20
  4. D.30
Show the answer and explanation

Answer: B (10)

Explanation

37a = a + (n − 1)4a gives 36a = 4a(n − 1), so n − 1 = 9 and n = 10.