The average age of 15 students is 15 years. If 5 students average 14 years and 9 others average 16 years, what is the age of the 15th student____________?
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Answer: A. 11 years
Explanation
The total cumulative age of all fifteen students is determined by multiplying the overall average. Subtracting the subgroup age sums from the total yields the specific age of the final student. The resulting age calculation for the fifteenth student equals exactly eleven years. The average value is calculated by dividing the sum of all elements by the count of elements. Cumulative sums of subsets can be subtracted from the grand total to find missing values. Basic arithmetic operations govern the manipulation of statistical averages and dataset sums.
Educational institutions track student age averages to monitor classroom demographics and grade distributions. Statistical analysis often requires recovering individual data points from aggregate subgroup summaries. Weight and age distribution problems appear frequently in standardized aptitude and reasoning assessments. Option b represents the average age of a subgroup rather than the missing individual's age. Option c matches the overall group average instead of the calculated age of the single student. Option d provides a fractional value that does not correspond to the exact integer result.
- Subject
- Mathematics
- Category
- Mathematics
- Topic
- —
- Difficulty
- medium
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