Answer:
The height of the wall is 2.7 m.
Explanation:
The number of blocks required = 2450. Each cubical block has a side of 20cm(0.2m).
But, volume = length × width × height.
So that,
       the volume of each block = (0.2  × 0.2  ×0.2) [tex]m^{3}[/tex]
                            = 0.008 [tex]m^{3}[/tex]
The total volume of the blocks to be used = 2450 × 0.008
                                   = 19.6 [tex]m^{3}[/tex]
The window has a measurement of 2.5m ×1m;
      its space volume = 2.5m ×1m × 0.4m
                     = 1.0 [tex]m^{3}[/tex]
The door has a measurement of 2m× 3m;
      its space volume = 2m× 3m × 0.4m
                    = 2.4[tex]m^{3}[/tex]
Thus, the window space and door space has a volume = 1.0 [tex]m^{3}[/tex] + 2.4[tex]m^{3}[/tex]
            = 3.4[tex]m^{3}[/tex]
Total volume of the wall = length × width × height
⇒ The total volume of the blocks - the window space and door space volume = length × width × height
The wall to be constructed has a length of 15m and width 40cm (0.4m).
So that the height could be determined as,
  19.6 [tex]m^{3}[/tex] - (3.4[tex]m^{3}[/tex]) = 15m × 0.4m × height
  16.2 [tex]m^{3}[/tex]  =  6[tex]m^{2}[/tex] ×height
⇒  height  = [tex]\frac{16.2}{6}[/tex]
  height = 2.7 m
Therefore, the height of the wall is 2.7m.
