Correct Answer - Option 3 : 180 km/h

**Given:**

Helicopter speed = 120 km/h

Time = 5 hours

**Formula Used:**

D = Speed × time

Speed = distance/time

**Calculation:**

Distance = Speed × time

⇒ 120 × 5

⇒ 600 km

∴ Required Speed = 600/(10/3)

⇒ 600 × (3/10)

⇒ 60 × 3

⇒ 180 km/h.

**∴**** the helicopter must travel at 180 km/h. **