CAPF AC 2025 Q62: General Mental Ability – Quantitative Aptitude

CAPF AC 2025, Paper I (General Ability and Intelligence) · General Mental Ability

1. (a) 8:05 PM
2. (b) 8:00 PM
3. (c) 7:55 PM
4. (d) 8:02 PM

Answer: (c) 7:55 PM

Explanation

A clock whose hands meet every 65 minutes

Given: the clock is set right at 8:00 AM. Its hands come together every 65 minutes (as measured by a correct watch).

How to think: in a correct clock the hands meet every 65 5/11 minutes (720/11).

This clock meets them every 65 minutes of real time, which is sooner, so it runs fast.

The clock gains 5 minutes in 12 hours.

Answer: (c) 7:55 PM.

Why each option is right or wrong

• (a) Incorrect. 8:05 PM would be right only for a slow clock.
• (b) Incorrect. The clock is not accurate, so the real time is not 8:00 PM.
• (c) CORRECT. The fast clock shows 12 hours when only 11 h 55 min have passed.
• (d) Incorrect. 8:02 PM does not follow from the 65-minute meeting interval.

Key point

Correct clock: hands meet every 65 5/11 min. If they meet every 65 real minutes, the clock is fast by 5/11 min per 65 min. In 12 clock-hours, real time is 720 × 65 ÷ (720/11) = 715 minutes, i.e. 7:55 PM.

Remember

True meeting gap 65 5/11; faster meeting means a fast clock, real time 7:55 PM.

Common mistakes

• Treating the 65 minutes as clock minutes, which flips the answer to 8:05 PM.
• Using 60 minutes as the correct meeting interval instead of 65 5/11.
• Forgetting to convert 715 minutes back into hours and minutes.

Exam tip

Educated guess: the faulty meeting gap (65) is shorter than the true gap (65.45), so the clock is fast and the real time is earlier than 8:00 PM. Only one option is earlier.

Sources

• R. S. Aggarwal, Quantitative Aptitude for Competitive Examinations, chapter on Clocks (hands coincide every 65 5/11 minutes)
• Abhijit Guha, Quantitative Aptitude for Competitive Examinations (Tata McGraw-Hill), chapter on Clocks

Practise CAPF AC PYQsTake a timed mock