Water flows at 5 km/h through a rectangular channel 1.5 m wide and 0.8 m deep. How much area can it cover with water 8 cm deep in 30 minutes?

Explanation

1. 01

   In one hour a length of 5 km = 5,000 m of water passes, so the flow is $1.5 \times 0.8 \times 5{,}000 = 6{,}000$ m³ per hour.

2. 02

   In 30 minutes: 3,000 m³.

3. 03

   Area = volume ÷ depth = $3{,}000 \div 0.08 = 37{,}500$ m².