Admission changes average weight: The average of 19 students is 15 kg. After admitting one new student, the new average becomes 14.8 kg. Find the weight of the new student.

Difficulty: Easy

Correct Answer: 11 kg

Explanation:


Introduction / Context:
Average shift problems involving the addition of one value are solved by recomputing totals before and after the change. The difference equals the added value.


Given Data / Assumptions:

  • Initial: 19 students, average 15 kg
  • After addition: 20 students, average 14.8 kg


Concept / Approach:
Compute initial total, compute new total, subtract to get the new student’s weight.


Step-by-Step Solution:

Initial total = 19 * 15 = 285 kgNew total = 20 * 14.8 = 296 kgWeight of new student = 296 - 285 = 11 kg


Verification / Alternative check:
With the new student at 11 kg, the total becomes 296 over 20 students, giving 14.8 kg average as stated.


Why Other Options Are Wrong:

  • 10.6, 10.8, 14.9, 12.5 kg: do not produce the new average when recalculated.


Common Pitfalls:
Using 19 in the second multiplication by mistake or misplacing decimals when multiplying 14.8 by 20.


Final Answer:
11 kg

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