To solve this, we need to calculate the speed Sujit must drive to reduce the journey time by 25%.

Step 1: Find the original distance

The formula for distance is: $\text{Distance} = \text{Speed} \times \text{Time}$

Sujit's original speed is 60 km/h, and the time is 40 minutes. Convert 40 minutes to hours: $40 \, \text{minutes} = \frac{40}{60} \, \text{hours} = \frac{2}{3} \, \text{hours}$

Thus, the distance is: $\text{Distance} = 60 \times \frac{2}{3} = 40 \, \text{km}$

Step 2: Find the reduced time

A 25% reduction in time means: $\text{Reduced time} = \text{Original time} - 0.25 \times \text{Original time} = 0.75 \times \text{Original time}$

$\text{Reduced time} = 0.75 \times \frac{2}{3} = \frac{1}{2} \, \text{hours} = 30 \, \text{minutes}$

Step 3: Calculate the new speed

To travel the same distance (40 km) in the reduced time ($\frac{1}{2}$ hour), the new speed is: $\text{Speed} = \frac{\text{Distance}}{\text{Time}} = \frac{40}{\frac{1}{2}} = 40 \times 2 = 80 \, \text{km/h}$

Final Answer:

Sujit must drive at a speed of 80 km/h to reduce the journey time by 25%.

---

Would you like further clarification or a breakdown of specific steps?
Here are 5 related questions you might explore:

1. How does changing speed affect fuel consumption for the same distance?
2. What would be Sujit's time if he drove at a speed of 100 km/h?
3. How would the answer change if the distance were doubled?
4. What is the relationship between speed, distance, and time in general?
5. How can you use graphs to visualize speed versus time for this scenario?

Tip: Always ensure that time is converted to consistent units (hours) when solving speed and distance problems.