Shiva switched on a bulb at 1:37:39 hours and switched it off on the same day at 11 : 28 : 32 hours. For how long was the bulb in switched-on-mode ? a)10 hours 09 mins 54 secs b) 9 hours 09 mins 06 secs c) 9 hours 50 mins 53 secs d) 12 hours 40 mins 07 secs

Options

A. 10 hours 09 mins 54 secs
B. 9 hours 09 mins 06 secs
C. 9 hours 50 mins 53 secs
D. 12 hours 40 mins 07 secs

Answer

To find out how long the bulb was in switched-on mode, we need to subtract the time when it was switched on from the time when it was switched off.

### Step-by-Step Solution:

1. **Identify the times:**
- Bulb switched on: 1:37:39 hours
- Bulb switched off: 11:28:32 hours

2. **Convert the times into seconds for easier subtraction:**
- Convert the "switched on" time:
- Hours to seconds: \(1 \times 3600 = 3600\) seconds
- Minutes to seconds: \(37 \times 60 = 2220\) seconds
- Seconds: \(39\) seconds
- Total for switched on time: \(3600 + 2220 + 39 = 5859\) seconds

- Convert the "switched off" time:
- Hours to seconds: \(11 \times 3600 = 39600\) seconds
- Minutes to seconds: \(28 \times 60 = 1680\) seconds
- Seconds: \(32\) seconds
- Total for switched off time: \(39600 + 1680 + 32 = 41212\) seconds

3. **Subtract the two times:**
- Time duration = Switched off time - Switched on time
- \(41212 - 5859 = 35353\) seconds

4. **Convert the result back into hours, minutes, and seconds:**
- Calculate hours: \(35353 \div 3600 = 9\) hours (with a remainder)
- Calculate remaining seconds: \(35353 - (9 \times 3600) = 35353 - 32400 = 2953\) seconds
- Calculate minutes: \(2953 \div 60 = 49\) minutes (with a remainder)
- Calculate remaining seconds: \(2953 - (49 \times 60) = 2953 - 2940 = 13\) seconds

5. **Final result:**
- The bulb was in switched-on mode for **9 hours, 49 minutes, and 13 seconds**.

### Conclusion:
The correct answer is **9 hours 49 minutes 13 seconds**, which does not match any of the provided options. However, based on the video transcript, the closest option is **c) 9 hours 50 mins 53 secs**.