Q 54. A sphere of 10.5 cm radius is melted and cast into a cuboid of maximum volume. The total surface area of such cuboid is approximately:

A. 1720

B. 1650

C. 1810

D. 1932

• volume of sphere=(4/3)*pi*r^3
  =(4/3)*pi*(10.5)^3
  on solving it comes 11*21*21
  let l=11,b=21,h=21
  so S=2(lb+bh+hl)
  =2(11*21+21*21+21*11)
  =2(231+441+231)
  =2*903
  =1806
  so option (C)
  
• 10 years agoHelpfull: Yes(43) No(18)
• how did you get 11*21*21?
• 9 years agoHelpfull: Yes(16) No(1)
• answer will be A.1720.
  volume of sphere=(4/3)*pi*r^3=volume of cube=a^3
  so,(4/3)*pi*(10.5)^3=a^3
  so,a=16.9
  now, surface area of cube=6*a^2=6*(16.9)^2=1720.
• 9 years agoHelpfull: Yes(9) No(10)
• 
  volume of sphere=(4/3)*pi*r^3
  =(4/3)*pi*(10.5)^3
  on solving it comes 11*21*21
  let l=11,b=21,h=21
  so S=2(lb+bh+hl)
  =2(11*21+21*21+21*11)
  =2(231+441+231)
  =2*903
  =1806
  
• 8 years agoHelpfull: Yes(3) No(1)
• Rakesh U r ri8 bro.thanx.
• 9 years agoHelpfull: Yes(1) No(8)
• @Rakesh plz expln why u wrote S=2(lb+bh+bl)
• 6 years agoHelpfull: Yes(0) No(0)