31,32,33 mohon bantuannya ,pakai cara..

31. R = 2r, T = 2t
V mula2=  1/3πr²t
V akhir = 1/3πR²T = 1/3π(2r)²(2t) = 1/3π.4r².2t = 8. 1/3πr²t
alias 8 kali volume mula2.
Jadi 8 x 880 = 7.040 cm³ (D)

32. Luas bola = 154 cm² = 4πr²
r² = 12,25 cm²
r = 3,5 cm

r tabung = r bola = 3,5 cm
Tinggi tabung = 4 x r bola = 14 cm

Luas permukaan tabung
L = 2πr² + 2πrt
L = 2πr(r+t)
L = 2.22/7.3,5(3,5+14)
L = 385 cm²