Attendance-based pay and fines: A worker is engaged over 120 days. He earns ₹20 for each working day and incurs a deduction (fine) of ₹3 for each non-working day. His total remuneration after 120 days is ₹560. How many days was he absent?

Difficulty: Easy

Correct Answer: 80

Explanation:


Introduction / Context:
This is a linear equation problem involving separate contributions for working and non-working days. The worker receives a positive amount per working day and a deduction per absence, resulting in a relatively small net amount over a long period, which implies many absences.


Given Data / Assumptions:

  • Total calendar days considered = 120
  • Payment per working day = ₹20
  • Deduction per non-working day = ₹3
  • Total remuneration = ₹560


Concept / Approach:
Let w = number of working days and a = number of absences. Then w + a = 120. Net pay = 20w - 3a. Solve the simultaneous equations for a.


Step-by-Step Solution:

w + a = 120 ⇒ w = 120 - aNet pay: 20w - 3a = 56020(120 - a) - 3a = 5602400 - 20a - 3a = 5602400 - 23a = 560 ⇒ 23a = 1840 ⇒ a = 1840 / 23 = 80


Verification / Alternative check:

w = 120 - 80 = 40Net = 20*40 - 3*80 = 800 - 240 = 560 (matches)


Why Other Options Are Wrong:

  • 60/70/40: Substituting these in w + a = 120 and 20w - 3a fails to produce ₹560.


Common Pitfalls:

  • Misinterpreting the deduction as reducing the pay per working day instead of subtracting per absence.
  • Arithmetic mistakes while simplifying 2400 - 23a = 560.


Final Answer:

80

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