Question

Water in a canal, 30 dm wide and 12 dm deep, is flowing with a speed of 10 km/hr. How much area will it irrigate in 30 minutes

Answer 1

measurements of canal=
l=10000m
b=30m
h=12m
water flow in 1 hr
=lbh
=10000×30×12
=3600000m³
water falling in 30 min=3600000/2
=1800000m3

Answer 2

Converting dm into m we know that,

1 dm = 1/10 m

30 dm = 30/10 m = 3 m

12 dm = 12/10 m = 1.2 m

Volume of water that flow from canal,

= 3 m × 1.2 m × 10 km/h

= 3 m × 1.2 m × 10 × 1000 m/h

= 3.6 m² × 10000 m/h

= 36000 m³/h

This volume of water accumulated for 30 mins

= 36000 m³/h × 30/60 hr

= 18000 m³

Since area × height = volume

Area = Volume/height

Area = 18,000 m³/ height in m

Area = 18000/h m²

Since you have not mentioned value of h.

So if you have forgotten to type whole question, then just put value of h.