A radius of the base of a right circular cone is 6 cm and its slant height is 28 cm. The curved surface area of the cone is?

Let their radii be x and 2x .
Ratio of their surface areas = [4?x²]/[4?(2x)²] = 1/4 = 1 : 4

Let their height be h and 2h radii be x and y respectively.
Then, ?x²h = ?y²(2h)
? x²/y² = 2/1
? x/y = ?2 / 1 = ?2 : 1

Let their radii be 2r and 3r and height 5h and 3h respectively.
? Ratio of their volumes = [?(2r)² x 5h] / [?(3r)² x 3h]
= 20/27 = 20 : 27

Original volume = 4/3?r³
New volume = 4/3 ? (2r)³ = 32/3 ?r³
Required increased % = [(28/3) ?r³] x [(3/4)?r³] x 100 % = 700 %

Original volume = 1/3 ?r²h;
New volume = 1/3 ?r²(2h) = 2/3?r²h

Required increased % = [?r²h/3]/[?r²h/3] x 100%
= 100%

Number of bullets = Volume of cube / Volume of 1 bullet
= (22 x 22 x 22)/(4/3 x 22/7 x 1 x 1 x 1)
= 2541.

Number of balls = Volume of big ball / Volume of 1 small ball
= [4/3 x ? x 10 x 10 x 10] / [4/3 x ? x 0.5 x 0.5 x 0.5]
= 8000

Total volume of cuboid = (10 x 5 x 2) cm³
= 100 cm³
Volume curved = 1/3 x (22/7) x 3 x 3 x 7 cm³
= 66 cm³
% of wood wasted = (100 - 66)% = 34 %

? (1/3)?r² x h = ?r² x 5
? h = 15 cm

? 1/3 ? x (2)² x h = ? x (2)² x 6
? h = 18 cm