Lesson 2.8: Clocks, Calendars & Time Problems

Introduction:
Clocks, calendars, and time-related problems are common in SSC exams. These questions test logical reasoning and mathematical calculation skills.

1. Clocks

• Types of Questions:

  1. Angle between hands of a clock

     • Formula:

$$\text{Angle}=|30H-(11/2)M|$$

Where H = hour, M = minutes
2. Time taken for hands to coincide or opposite
3. Minute hand, hour hand speed, and relative movement

• Example:
  Time = 3:20

Angle=∣30×3−(11/2)×20∣=∣90−110∣=20∘\text{Angle} = |30 \times 3 – (11/2) \times 20| = |90 – 110| = 20^\circAngle=∣30×3−(11/2)×20∣=∣90−110∣=20∘

2. Calendars

• Types of Questions:

  1. Day of the week for a given date

  2. Number of Sundays/Fridays in a month/year

  3. Leap year calculations

• Tips:

  • Use Zeller’s Congruence or shortcut methods

  • Remember month codes and leap year rules

3. Time & Work / Time & Distance Problems

• Time & Work:

$$\text{Work}=\text{Rate}\times \text{Time}$$

• Time & Distance:

Speed=DistanceTime\text{Speed} = \frac{\text{Distance}}{\text{Time}}Speed=TimeDistance​

• Tips: Use unitary method for speed, distance, and time conversions.

4. Practice Questions

1. Find the angle between hands at 7:15.

2. If hands coincide at 2:00, how many times do they coincide in 12 hours?

3. 1 person completes a work in 8 days, another in 12 days. Together, how long?

4. 60 km covered in 1 hour 20 minutes. Find speed in km/h.

5. 15th August 2025 falls on which day of the week?