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WAEC Mathematics 2014 Question 48

Question 48

Progressions

Find the number of terms in the Arithmetic Progression (A.P.) 2, −9, −20, …, −141.

  1. A.11
  2. B.12
  3. C.13
  4. D.14
Show the answer and explanation

Answer: D (14)

Explanation

a = 2, d = −11: 2 + (n − 1)(−11) = −141, so n − 1 = 13 and n = 14.