Jammutavi express leaves jammu for kanya kumari at 120 km/h and returns to jammu at 80 km/h what is the average speed of the train during the whole journey?

Options

A. 47.5 km/h
B. 96 km/h
C. 38 km/h
D. 57.5 km/h

Answer

To find the average speed of the Jammu Tavi Express during the whole journey, we can use the formula for average speed when the distances are the same but the speeds are different for the two parts of the journey.

### Step-by-Step Solution:

1. **Identify the Speeds**:
- Speed while going from Jammu to Kanyakumari (A) = 120 km/h
- Speed while returning from Kanyakumari to Jammu (B) = 80 km/h

2. **Use the Average Speed Formula**:
The formula for average speed when the distance is the same is given by:
\[ \text{Average Speed} = \frac{2AB}{A + B} \]
where A is the speed for the first part of the journey and B is the speed for the return journey.

3. **Substitute the Values**:
Substitute A and B into the formula:
\[ \text{Average Speed} = \frac{2 \times 120 \times 80}{120 + 80} \]

4. **Calculate the Denominator**:
First, calculate the sum of A and B:
\[ 120 + 80 = 200 \]

5. **Calculate the Numerator**:
Now calculate the product in the numerator:
\[ 2 \times 120 \times 80 = 19200 \]

6. **Final Calculation**:
Now divide the numerator by the denominator:
\[ \text{Average Speed} = \frac{19200}{200} = 96 \text{ km/h} \]

### Conclusion:
The average speed of the Jammu Tavi Express during the whole journey is **96 km/h**.