Velocity calculation of a trapizoidal channel section

Problem: Calculate the velocity of a trapizoidal section if the discharge is 11.25 m³/s.Side slope 1:1 and bottom width 6m and depth of flow is 1.5m?
Exam Name: BGFCL 2017, BCIC 2016

Solution: 
We know,
              V= Q/A
              
Here, Q=11.25  m³/s
          A = (b+nh)h
              = (6+1*1.5)*1.5
              = 11.25  m²

  ∴V= Q/A 
       =  11.25/ 11.25     
       =  1 m/s  

Answer:    1 m/s         

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