Water in a canal, 6 m wide and 1.5 m deep, is flowing with a speed of 10 km/h. How much area will it irrigate in 30 minutes, if 8 cm of standing water is needed?

Width of canal = 6 m, depth of canal = 1.5 m
Speed of water = 10 km /h = 1000/60 m/min
Volume of water in 1 minite = 6 × 1.5 × 1000/60 = 1500m³
Therefore, the volume of water in 30 minutes
= 30 × 1500 = 45000 m³
Let the area of irrigated field = A m²
Therefore,
Volume of water from canal in 30 minutes = volume of water in the field
⇒ 45000 = (A × 8/100)
⇒ A = (45000 × 100/8) = 562500 m²
Hence, canal irrigate 562500 m² area is 30 minutes.