The average monthly salary of 9 workers and one supervisor in a factor was…

2023

The average monthly salary of 9 workers and one supervisor in a factor was 8700 Rs per month . after retiring of a worker , a new supervisor was appointed and the average salary of 10 people was 8900 Rs per month then the difference between the monthly salary of a worker and a supervisor is -

  1. A.

    Rs. 3000

  2. B.

    Rs. 1500

  3. C.

    Rs. 2500

  4. D.

    Rs. 2000

Attempted by 23 students.

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Correct answer: D

Answer: Rs. 2000

Let the monthly salary of a worker be x and that of a supervisor be y.

  1. Total salary of 9 workers and 1 supervisor: 9x + y = 10 × 8,700 = 87,000.

  2. After the change (one worker replaced by a supervisor): 8x + 2y = 10 × 8,900 = 89,000.

  3. Divide the second equation by 2 to simplify: 4x + y = 44,500.

  4. Subtract the simplified second equation from the first: (9x + y) − (4x + y) = 87,000 − 44,500 ⇒ 5x = 42,500 ⇒ x = 8,500.

  5. Substitute x into 9x + y = 87,000 to find y: y = 87,000 − 9 × 8,500 = 10,500.

  6. Difference between supervisor and worker = y − x = 10,500 − 8,500 = 2,000.

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