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