Question

A river is 2 m deep and 30 m wide is flowing at the rate of 4 km per hour. How much water will into the sea after 30 minutes? 
1. 120000 m³
2. 1900 m³
3. 20894 m³
4. 78000 m³

Answer 1

Correct Answer - Option 1 : 120000 m³

Given: 

Height = 2 m

Breadth = 30 m

Flowing rate = 4 km/hr.

Formula Used:

The volume of cuboid = length × Breadth × Height

Calculation: 

Flowing rate = 4 km/hr.

Water travelling rate in 1 hour = 4km

So, water travel in 60 minutes = 4000m

Therefore water travel in 1 minute = 4000/60

Volume of cuboid = Volume of water flow in 1 minute = 2 × 30 × 4000/60 

⇒ Volume of water flow in 1 minute = 240000/60 = 4000 m³

⇒ Volume of water flow in 30 minutes = 4000 × 30 = 1,20,000 m³

∴ In 30 minutes 120000m³ water will come into the sea.

The correct option is 1 i.e. 120000m3.