Q12 of 32 Page 13

Find the volume of a cube whose total surface area is given:
(i) 486 cm2 (ii) 54 cm2 (iii) 150 cm2

Let the edge of the cube= a cm
Then total surface area=6a2 cm2
and volume of the cube=a3 cu. cm.
  
(i) 6a2 = 486   ⇒   a=9 cm
Hence volume=(9)3=729 cm3
  
(ii) 6a2=54      ⇒    a = 3 cm
Hence volume=(3)3=27 cu. cm.
 
(iii) 6a2=150  ⇒   a=5 cm
Hence volume=(5)3=125 cu. cm.

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