Number series – supply the next two terms. Given sequence: 40, 40, 31, 31, 22, 22, 13, ____ , ____
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A13 13
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B13 4
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C9 9
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D22 22
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E4 4
Answer
Correct Answer: 13 13
Explanation
Introduction / Context:This question assesses recognition of a repeating-pair pattern where each value appears twice before stepping down by a constant amount. We must extend the series correctly and avoid distractors that look similar but break the rule.
Given Data / Assumptions:
- Sequence: 40, 40, 31, 31, 22, 22, 13, …
- We need the next two terms immediately after the single 13 shown.
- No hidden operations; standard integer patterning.
Concept / Approach:Many sequences replicate each term twice, then reduce by a fixed decrement. Identify the decrement and preserve the duplication rule.
Step-by-Step Solution:
Group terms: (40, 40), (31, 31), (22, 22), (13, __).Compute the decrement: 40 → 31 is -9; 31 → 22 is -9; 22 → 13 is -9.Each value appears twice before stepping down by 9.Since 13 appears only once so far, the next term must repeat 13.Therefore, the next two terms are: 13, 13.Verification / Alternative check:The pattern 'repeat, repeat, decrement by 9' holds across all blocks. No evidence supports a new decrement now, so duplication of 13 is required before any further reduction (to 4, which would be the next block’s value).
Why Other Options Are Wrong:
- 13 4: Jumps to the next block prematurely; 13 must repeat first.
- 9 9: Implies a -4 step, contradicting the -9 rule.
- 22 22: Repeats an old block; sequence has already moved on.
- 4 4: Would be correct only after completing the 13,13 pair.
Common Pitfalls:Learners often compute the next 'new' value (4) and forget the duplication rule. Always check whether the current value has appeared once or twice.
Final Answer:13 13