The average salary of 15 teachers is Rs. 4,500 per month, 5 teachers now leave the school. The average salary of the remaining 10 teachers now is Rs. 4,200 per month. Find the total salary per month of the 5 teachers who left the school.

1. A

   Rs. 24,000

2. B

   Rs. 25,000

3. C

   Rs. 27,000

4. D

   Rs. 25,500

Appeared in: RRB Staff Nurse Kolkata-2015

Explanation

• The core principle is that Total Value = Average × Number of Items.
• First, calculate the total salary for the initial group of 15 teachers: 15 × Rs. 4,500 = Rs. 67,500.
• Next, calculate the total salary for the remaining group of 10 teachers: 10 × Rs. 4,200 = Rs. 42,000.
• The total salary of the 5 teachers who left is the difference between the initial total and the final total: Rs. 67,500 - Rs. 42,000 = Rs. 25,500.

Why Other Options Were Wrong

• Option A: This value (Rs. 24,000) is the result of a calculation error. It does not correspond to the correct difference between the initial and final total salaries.
• Option B: This value (Rs. 25,000) is a rounded number close to the correct answer. It likely arises from rounding during calculation or a minor arithmetic mistake.
• Option C: This value (Rs. 27,000) is incorrect. It might be obtained by incorrectly multiplying one of the given numbers, for instance, 6 teachers × Rs. 4,500 = Rs. 27,000, which is not a relevant calculation.

Related Visual

• Visual 1: Flowchart: A simple flowchart can illustrate the calculation process. Step 1: Calculate Initial Total Salary (15 × 4500). Step 2: Calculate Final Total Salary (10 × 4200). Step 3: Subtract Final from Initial to find the salary of the departed group.

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculation of averages and totals in word problems as background academic context rather than a clinical decision trigger.
• Understanding how to work with averages is a fundamental mathematical skill essential for data interpretation in many fields, not just nursing.
• This type of calculation is directly applicable in administrative roles, such as hospital management, for budgeting, payroll analysis, and resource allocation.
• What if? If the average salary of the remaining 10 teachers had increased to Rs. 4,600, it would imply that the 5 teachers who left had a lower average salary than the group. The calculation would be (15 × 4,500) - (10 × 4,600) = 67,500 - 46,000 = Rs. 21,500.

How to Approach the Question

• First, identify all the numerical data provided in the problem: initial number of teachers (15), initial average salary (Rs. 4,500), number of teachers who left (5), and the new average salary (Rs. 4,200).
• Recognize that the question asks for the total salary of the group that left, not their average salary.
• Recall the relationship between total, average, and number: Total = Average × Number.
• Apply this formula to find the total salary of the original group of 15 teachers.
• Apply the formula again to find the total salary of the remaining group of 10 teachers.
• Subtract the second total from the first total. The result is the total salary of the 5 teachers who left.

Concept Tested & Keywords

• Concept Tested: Calculation of averages and totals in word problems.
• Stem keywords: average salary, teachers, leave the school, remaining teachers
• Lead-in keywords: Find the total salary

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Q9TxxzVLct1IWe76eMV1iL

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