Consider the following arrangement that has some missing letters: a b _ b b _…
2024
Consider the following arrangement that has some missing letters:
a b _ b b _ a b a _ b a _ b a b _ a
Which one set of letters when subsequently placed at the gaps in the above letter series shall complete it?
- A.
aabab
- B.
bbabb
- C.
abbbab
- D.
aaaaab
Attempted by 1092 students.
Show answer & explanation
Correct answer: A
Key idea: the sequence is produced by repeating a short block of letters.
Try the 5-letter block a a b a b (written as "aabab"). Repeating that block gives:
a a b a b | a a b a b | a a b a b ...
Overlaying this repetition onto the given series fills every blank while matching the letters that are already shown. Therefore the missing letters must be the block "aabab".
Why the other choices fail:
"bbabb" would place b where the sequence has a (for example at the start), so it cannot match the known letters.
"abbbab" is six letters long and contains three b's in a row; repeating it would create patterns that contradict the visible letters and does not fit the observed 5-letter repetition.
"aaaaab" creates long runs of a that conflict with known b positions in the series, so it does not align with the given letters.
Conclusion: the correct block to fill the blanks is "aabab".