UPSC Prelims 2019·CSAT·Logical Reasoning·Series and Sequences

Consider the following sequence that follows some arrangement: c_accaa_aa_bc_b The letters that appear in the gaps are

Dalvoy logo
Reviewed by Dalvoy
UPSC Civil Services preparation
Last updated 23 May 2026, 3:31 pm IST
  1. Aabba
  2. BcbbbCorrect
  3. Cbbbb
  4. Dcccc

Explanation

To solve this, we first look at the total number of positions in the sequence, which is 15. We can divide this into three groups of five letters each. The sequence with the gaps is c _ a c c | a a _ a a | _ b c _ b. By placing the letters from option B (c, b, b, b) into the gaps, we get: ccacc | aabaa | bbcbb Each group follows a specific pattern where the middle letter is different from the four surrounding identical letters. In the first group, c surrounds a. In the second group, a surrounds b. In the third group, b surrounds c. This creates a logical rotating pattern among the letters a, b, and c. Therefore, option B is the correct choice because it completes a consistent structural arrangement.
Logical Reasoning: Consider the following sequence that follows some arrangement: c_accaa_aa_bc_b The letters that appear in the gaps are
ShareWhatsAppXTelegram

Related questions

More UPSC Prelims practice from the same subject and topic.