What is the surface area of a sphere with a circumference of 50ft?
a. 63.3ft^2
b. 198.9ft^2
c. 398.0ft^2
d. 795.8 ft^2
the volume of a sphere if 2,254pi m^3. what is the surface area of the sphere to the nearest 10th?
a. 831.4 m^2
b. 891.6 m^2
c. 1,22.0 m^2
d. 1,1783.3 m^2
what is the scale factor of a cube with a volume 729 m^3 to a cube with volume of 6,859 m^3 ?
a. 19: 9
b. 9: 19
c. 361: 81
d. 81: 361

Sphere
c=2pir
v=(4/3)pir^3
SA=4pir^2

so

first one
c=50
50=2pir
25=pir
25/pi=r
SA=4pir^2
SA=4pi(25/pi)^2
SA=4pi625/(pi^2)
SA=2500/pi
SA=795.8
D

2nd euqtion
V=2254pi
(4/3)pir^3=2254pi
divide both sides by pi
(4/3)r^3=2254
ties both sides by 3/4
r^3=1690.5
cube root both sides
r=11.9126
SA=4pir^2
SA=4pi11.9126^2
SA=4pi141.909
SA=567.636pi
SA=1783.3
D is answer

3rd
find side legnth
cube root each since V=side^3
volume 729 to 6859 is side legnths
9 to 19
every 9 units turns to 19

answer is A

D
D
A