How many bullets can be made out of a cube of lead whose edge measures 22 cm, each bullet being 2 cm in diameter?

Curved surface area = ?rl
= (22/7 x 6 x 28) cm²
= 528 cm²

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 %

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

Since the diameters are in the ratio 4 : 5. It follows that their radii are in the ratio 4 : 5.
Let them be 4r and 5r. Let the height be h and H .
? Ratio of volumes = [(1/3)?(4r)²h / (1/3)?(5r)²H
= (16h)/(25H)
? h/H = (1/4) x (25/16) = 25/64 = 25: 64.