A clock loses 5 minutes every hour and was set right at 11AM on a Monday. When…
2026
A clock loses 5 minutes every hour and was set right at 11AM on a Monday. When will it show the correct time again?
- A.
11AM on Sunday
- B.
11AM on Monday
- C.
11AM on Tuesday
- D.
11AM on Wednesday
Attempted by 3 students.
Show answer & explanation
Correct answer: A
On a standard 12-hour analog dial, a clock that drifts (gains or loses time) at a constant rate displays the correct time again only once its cumulative error reaches a full 12-hour cycle (720 minutes) — because a shift of exactly 12 hours brings the hour and minute hands back to the same face position as the correct time.
The clock loses 5 minutes for every 60 minutes (1 hour) of actual elapsed time.
For the clock to show the correct time again, its cumulative loss must reach a full 12-hour cycle = 12 × 60 = 720 minutes.
Real time required = (720 minutes of loss) ÷ (5 minutes lost per 60 real minutes) = 720 × (60/5) = 8640 minutes.
Convert to hours: 8640 ÷ 60 = 144 hours.
Convert to days: 144 ÷ 24 = 6 days.
Starting from 11 AM on Monday, adding 6 days lands on 11 AM the following Sunday.
Cross-check: each hour of drift costs 60 ÷ 5 = 12 real hours to accumulate, so the full 12-hour cycle takes 12 × 12 = 144 real hours — the same 6 days, confirming the result independently.
Hence, the clock next shows the correct time at 11 AM on Sunday.