So, in order to answer this question, let us analyse the given data

it says that the **depth = 3 metres**

width = 40 metres

and the rate of flow = 2 km per hour( converting this into metre per second, we get rate of flow = 2*(1000/3600)=2*(5/18)= 0.55 metre per second)

now we know that** volume = length *width*height**

similarly,** volumetric rate of flow = length*width*rate of flow**

which leaves us at** v=3*40*0.55= 66.67 metre cube per second. **

so the amount of flow per minute would be given by

66.67*60 = 4000 metre cube per minute

pls do let me know if the answer helped