A class of 35 students averages 16 years of age. If 21 students average 14 years, what is the average age of the remaining 14?
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Answer: D. 19 years
Explanation
The total age sum of all thirty five students is calculated by multiplying the class size by the mean age. Subtracting the total age sum of the first group from the overall total gives the remaining age sum. Dividing the remaining age sum by the number of remaining students yields their average age. The arithmetic mean is calculated by dividing the sum of all values by the total count of items. Weighted group averages allow statisticians to combine separate subgroups into a single population metric. Total aggregate values remain invariant regardless of how the underlying subgroup partitions are analyzed.
Schools track cohort age averages to monitor student progression and plan appropriate grade level activities. Demographic studies use grouped averages to analyze population characteristics across different age brackets. Human resource departments evaluate employee tenure averages to understand workforce experience distribution. Option A underestimates the average age by failing to properly account for the remaining age sum. Option B represents an incorrect intermediate calculation derived from faulty subgroup weighting. Option C is slightly too low and results from a minor arithmetic error in the division step.
- Subject
- Mathematics
- Category
- Mathematics
- Topic
- —
- Difficulty
- medium
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