Sachin and Mongiya starting from the same place walk at the rate of 7.5 km/h and 9 km/h respectively. What time will they take to be 7.5 km apart, if they walk in the same direction?

Options

A. 3 h
B. 4 h
C. 5 h
D. none of these

Answer

To solve the problem, we need to determine how long it will take for Sachin and Mongiya to be 7.5 km apart while walking in the same direction.

### Step-by-Step Solution:

1. **Identify the speeds of both individuals:**
- Speed of Sachin = 7.5 km/h
- Speed of Mongiya = 9 km/h

2. **Calculate the relative speed:**
- Since they are walking in the same direction, the relative speed is the difference between their speeds.
- Relative Speed = Speed of Mongiya - Speed of Sachin
- Relative Speed = 9 km/h - 7.5 km/h = 1.5 km/h

3. **Use the formula for time:**
- Time = Distance / Relative Speed
- Here, the distance we want them to be apart is 7.5 km.
- Time = 7.5 km / 1.5 km/h

4. **Calculate the time:**
- Time = 7.5 / 1.5 = 5 hours

### Final Answer:
Sachin and Mongiya will take 5 hours to be 7.5 km apart if they walk in the same direction.

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