Production dip and monthly average: A TV factory produces on average 60 sets/day for the first 25 days of a month. Illness lowers output over the last 5 days so that the monthly average becomes 58. What is the average production per day during the last 5 days?
Aptitude
Average
Difficulty: Easy
Choose an option
Answer
Correct Answer: 48
Explanation
Introduction / Context:Block averages (first 25 days, last 5 days) can be combined via totals to reach the monthly average. Subtract the known block to get the unknown block's total and divide by its length.Given Data / Assumptions:
- First 25 days average = 60 ⇒ total = 1500.
- Monthly average = 58 across 30 days ⇒ total = 1740.
- Need average over last 5 days.
Concept / Approach:Last 5 days total = monthly total − first 25 days total. Then divide by 5.Step-by-Step Solution:
Monthly total = 30 * 58 = 1740First-25 total = 25 * 60 = 1500Last-5 total = 1740 − 1500 = 240Average last 5 = 240 / 5 = 48Verification / Alternative check:Weighted average check: (1500 + 240)/30 = 1740/30 = 58. Works.Why Other Options Are Wrong:
- 45 or 52: Would yield monthly totals different from 1740.
- 58: That is the monthly average, not the last 5-day average after a dip.
Common Pitfalls:Averaging 60 and 58 directly instead of using totals and correct day counts.Final Answer:
48