the length of a cinema hall 20metre its width is 16 cm. the sum of the areas of its floor and flat roof is equal to the surface area of four walls find volumes and height of hall?

Area of the floor = l x b 

 

                        = 20 x 16 = 320 sq m 

 

area of the roof = 20 x 16 = 320 sq m 

 

 

sum of the areas of the four walls = 2 ( l + b ) .h 

 

hence 2 ( 20 + 16 ) h = 72h sq m.

 

now 72 h = 320 + 320

 

       72h = 640

 

hence  h = 640 / 72 =   80 / 9 m