Difficulty: Hard
Correct Answer: 643
Explanation:
Introduction / Context:
This is a higher level number series question where the pattern is not immediately obvious from simple first differences or simple multiplication. Such questions test your ability to look beyond direct differences and to consider second level patterns such as differences of differences. Being comfortable with these ideas is very useful for tough aptitude tests and competitive exams.
Given Data / Assumptions:
Concept / Approach:
First we look at the differences between consecutive terms, and then at the differences between those differences. When first differences are irregular, series often follow a pattern in their second differences. If the second differences follow an arithmetic pattern, we can extend that pattern to find the next first difference and in turn the next term of the series.
Step-by-Step Solution:
Step 1: Compute first differences: 24 - 5 = 19, 94 - 24 = 70, 279 - 94 = 185.Step 2: Compute second differences between these: 70 - 19 = 51, 185 - 70 = 115.Step 3: Notice that these second differences themselves increase. The increase from 51 to 115 is 64.Step 4: Continue this logical pattern by adding another 64 to 115, giving the next second difference as 115 + 64 = 179.Step 5: Find the next first difference: previous first difference 185 plus new second difference 179 gives 185 + 179 = 364.Step 6: Add this first difference to the last known term: 279 + 364 = 643, which must be the next term in the series.
Verification / Alternative check:
We can verify by writing down the pattern of second differences explicitly as 51, 115, and then 179, showing that each time the increment applied is 64. This is consistent and produces a unique next term. None of the other options will maintain this smooth pattern in second differences, which confirms that 643 is the only value that fits the intended structure.
Why Other Options Are Wrong:
Values like 587, 554, 499, and 489 do not give a consistent sequence of second differences when inserted as the next term. In each of those cases, the second level differences either jump randomly or do not maintain a regular increment of 64. Hence they break the discovered pattern and cannot be correct.
Common Pitfalls:
Many students stop after checking only first differences or try to guess a direct multiplication pattern. Because the multipliers and additions look irregular at first glance, guesses often fail. The safer method is to compute second differences systematically. Not recognizing that some series are built on second level patterns is a frequent issue in tough number series questions.
Final Answer:
The correct next term in the series is 643.
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