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GATE 2020 CE (CE1) – Question 8

General Aptitude · Quantitative Aptitude: Algebra, Geometry and Mensuration · 2 marks · Multiple choice

Insert seven numbers between 2 and 34 so the resulting sequence, including the endpoints, is an arithmetic progression. Find the sum of the inserted numbers.

  1. 120
  2. 124
  3. 126
  4. 130

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Correct answer: (C) 126

Explanation

Including endpoints there are nine terms and eight gaps, so $d=(34-2)/8=4$. Inserted terms run from 6 to 30. Their sum is $7(6+30)/2=126$. **C**.