Explanation:

Alright, let’s break everything down step by step:

- The distance to the shop is 10 km, and it took 50 minutes to get there.

- Speed going to the shop: \(10 \text{ km} / (50/60 \text{ hr}) = 10 / (5/6) = 12 \text{ km/hr}\)

- On the way back, he takes 10 minutes less. So: \(50 - 10 = 40\) minutes.

- Speed returning: \(10 \text{ km} / (40/60 \text{ hr}) = 10 / (2/3) = 15 \text{ km/hr}\)

- Speed increase: \(15 - 12 = 3 \text{ km/hr}\) This matches option 1.

About the cylinder and cone:

- Cylinder volume: 4620 m³

- Volume of cone: \(\frac{1}{7}\) of 4620 = 660 m³; Height = 10 m.

None of this affects the speed question. It’s just context.

So here’s the real answer: The student increased his speed by 3 km/hr on the way back.

Option 1 is the correct answer.