A train starts form station `A` at 1pm and reaches station `B` at 3pm, after travelling 108 km. It halts at station `B` for one hour and then starts for station `C` which is 42 km from station `B`. It reaches station `C` at 7pm on the same day. The average speed of the train for the whole journey from `A` to `C` is

Options

A. `68 km//hr`
B. `25 km//hr`
C. `30 km//hr`
D. `35 km//hr`

Explanation

To find the average speed of the train for the whole journey from station A to station C, we will follow these steps:

### Step 1: Calculate the total distance traveled
The train travels from station A to station B and then from station B to station C.

- Distance from A to B = 108 km
- Distance from B to C = 42 km

**Total Distance = Distance from A to B + Distance from B to C**
\[ \text{Total Distance} = 108 \text{ km} + 42 \text{ km} = 150 \text{ km} \]

### Step 2: Calculate the total time taken
The total time includes the time taken to travel from A to B, the halt at B, and the time taken to travel from B to C.

- Time taken from A to B = 3 PM - 1 PM = 2 hours
- Halt at B = 1 hour
- Time taken from B to C = 7 PM - 4 PM = 3 hours (since it starts at 4 PM after the halt)

**Total Time = Time from A to B + Halt at B + Time from B to C**
\[ \text{Total Time} = 2 \text{ hours} + 1 \text{ hour} + 3 \text{ hours} = 6 \text{ hours} \]

### Step 3: Calculate the average speed
Average speed is defined as the total distance traveled divided by the total time taken.

\[ \text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}} = \frac{150 \text{ km}}{6 \text{ hours}} = 25 \text{ km/h} \]

### Conclusion
The average speed of the train for the whole journey from station A to station C is **25 km/h**.

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