Reasoning: How to Solve Clock, Time Gained-Lost, Fast-Slow Clock in a Given Period

Introduction "Mastering clock time gained/lost can fetch you 5-10 marks in a single question, making it a must-know topic for SSC, Banking, Railway, and CUET exams."

WHAT YOU NEED TO KNOW FIRST To solve clock time gained/lost questions, you need to remember:

1. Direction Chart: A simple chart to determine the direction of the clock (fast or slow) based on the given time period.
2. BODMAS: The order of operations to simplify complex expressions (Brackets, Orders, Division, Multiplication, Addition, and Subtraction).
3. Sitting Arrangement Conventions: Understanding how people sit in a room, including the direction they face and the order in which they perform tasks.

CRYSTAL‑CLEAR METHOD (Step‑by‑Step) To solve clock time gained/lost questions:

1. Read the question carefully: Understand the time period and the direction of the clock (fast or slow).
2. Identify the key information: Note the time at which the clock is fast or slow and the time period.
3. Use the direction chart: Determine the direction of the clock based on the given time period.
4. Calculate the time gained/lost: Use the direction chart to calculate the time gained or lost.
5. Simplify the expression: Apply BODMAS to simplify the expression.
6. Check the answer: Verify the answer by plugging in the values.

WORKED EXAMPLES

Example 1 – Easy A clock is 5 minutes slow at 9:00 AM. How much time will it gain by 12:00 PM?

1. Read the question carefully: The clock is 5 minutes slow at 9:00 AM.
2. Identify the key information: The clock is slow by 5 minutes at 9:00 AM, and we need to find the time gained by 12:00 PM.
3. Use the direction chart: Since the clock is slow, it will gain time.
4. Calculate the time gained: The clock is slow by 5 minutes at 9:00 AM, so it will gain 5 minutes by 12:00 PM.
5. Simplify the expression: No simplification needed.
6. Check the answer: The clock will gain 5 minutes by 12:00 PM.

What we learned: To solve easy clock time gained/lost questions, focus on identifying the key information and using the direction chart.

Example 2 – Medium A clock is 10 minutes fast at 8:00 AM. If it loses 5 minutes every hour, how much time will it lose by 10:00 AM?

1. Read the question carefully: The clock is 10 minutes fast at 8:00 AM and loses 5 minutes every hour.
2. Identify the key information: The clock is fast by 10 minutes at 8:00 AM, and it loses 5 minutes every hour.
3. Use the direction chart: Since the clock is fast, it will lose time.
4. Calculate the time lost: The clock loses 5 minutes every hour, so it will lose 2 hours x 5 minutes = 10 minutes by 10:00 AM.
5. Simplify the expression: Apply BODMAS to simplify the expression.
6. Check the answer: The clock will lose 10 minutes by 10:00 AM.

What we learned: To solve medium clock time gained/lost questions, focus on identifying the key information, using the direction chart, and applying BODMAS.

Example 3 – Exam‑Style A clock is 15 minutes slow at 7:00 AM. If it gains 2 minutes every hour, how much time will it gain by 11:00 AM?

1. Read the question carefully: The clock is 15 minutes slow at 7:00 AM and gains 2 minutes every hour.
2. Identify the key information: The clock is slow by 15 minutes at 7:00 AM, and it gains 2 minutes every hour.
3. Use the direction chart: Since the clock is slow, it will gain time.
4. Calculate the time gained: The clock gains 2 minutes every hour, so it will gain 4 hours x 2 minutes = 8 minutes by 11:00 AM.
5. Simplify the expression: Apply BODMAS to simplify the expression.
6. Check the answer: The clock will gain 8 minutes by 11:00 AM.

What we learned: To solve exam-style clock time gained/lost questions, focus on identifying the key information, using the direction chart, and applying BODMAS under time pressure.

Common Mistakes

MISTAKE → WHY IT HAPPENS → CORRECT APPROACH 1. Not reading the question carefully: Not understanding the time period and direction of the clock. Correct Approach: Read the question carefully and identify the key information. 2. Not using the direction chart: Not determining the direction of the clock. Correct Approach: Use the direction chart to determine the direction of the clock. 3. Not applying BODMAS: Not simplifying complex expressions. Correct Approach: Apply BODMAS to simplify complex expressions. 4. Not checking the answer: Not verifying the answer. Correct Approach: Check the answer by plugging in the values. 5. Not considering the time period: Not taking into account the time period. Correct Approach: Consider the time period when calculating the time gained or lost.

EXAM TRAPS

Trap → How to Spot it → How to Avoid it 1. Trick question: The question seems easy but has a hidden twist. How to Spot It: Read the question carefully and identify the key information. How to Avoid It: Be cautious and take your time to read the question carefully. 2. Misleading information: The question provides misleading information. How to Spot It: Identify the key information and use the direction chart. How to Avoid It: Focus on the key information and use the direction chart. 3. Complex expressions: The question involves complex expressions. How to Spot It: Apply BODMAS to simplify complex expressions. How to Avoid It: Apply BODMAS to simplify complex expressions.

TIME‑SAVING SHORTCUTS

1. Elimination trick: Eliminate options that are not possible based on the direction chart.
2. Diagram hack: Use a diagram to visualize the clock and the time period.
3. Pattern recognition: Recognize patterns in the clock time gained/lost questions.

1‑MINUTE RECAP "Alright, let's recap. To solve clock time gained/lost questions, remember to read the question carefully, identify the key information, use the direction chart, calculate the time gained or lost, simplify the expression, and check the answer. Don't make common mistakes like not reading the question carefully, not using the direction chart, or not applying BODMAS. Be cautious of exam traps like trick questions, misleading information, and complex expressions. Use time-saving shortcuts like elimination tricks, diagram hacks, and pattern recognition. Practice, practice, practice, and you'll master clock time gained/lost in no time. Good luck on your exam!