Answer:
C=2πr
30cm=2πr
30cm/2π =2πr/2π
15πcm=r
uhm i would say the second one but i might be very wrong
Step-by-step explanation:
yes
yes it is im pretty sure
1 and 4
2 and 3
= volume. So then we need the radius which would be 5. So, 
= about 523.3 cm cubed