If a clock takes 7 seconds to strike 7, how long will the same clock take to…
2025
If a clock takes 7 seconds to strike 7, how long will the same clock take to strike 10?
- A.
10 seconds
- B.
10.5 seconds
- C.
11 seconds
- D.
12 seconds
Show answer & explanation
Correct answer: B
For a clock that strikes N times, the number of gaps between the strikes is N − 1, not N. The total striking time is spread evenly across these gaps, so the time taken per gap is a fixed rate for a given clock.
Striking 7 involves 7 − 1 = 6 gaps, and this takes 7 seconds in total.
So the time per gap for this clock is 7 ÷ 6 seconds.
Striking 10 involves 10 − 1 = 9 gaps.
Total time for 10 strikes = 9 × (7 ÷ 6) = 10.5 seconds.
Cross-check with the unitary method directly: 6 gaps correspond to 7 seconds, so 9 gaps correspond to (9 × 7) ÷ 6 = 10.5 seconds — the same result.
Therefore, the clock takes 10.5 seconds to strike 10.