Question

the volume of a sphere is 80 pi cm3. What is its surface area to the nearest whole number?

Answer 1

how would i solve this i have no clue. @

Answer 2

First calculate the sphere's radius by solving the following for r.

Answer 3

(4/3) pi r^3=80

Answer 4

I hope you know rob meant
(4/3) pi r^3=80 pi

Answer 5

to find r^3, divide both sides by pi
then multiply both sides by ¾

you should end up with
r^3 = some number
then take the "cube root" of both sides
that will give you
r= some number

Answer 6

once you know r, you can use the formula for the area of a sphere
A= 4 pi r^2

Answer 7

Volume = (4/3) * PI * radius^3
80 * PI = (4/3) * PI * radius^3
The 'PI's' cancel out leaving
80 = (4/3) * radius^3
radius^3 = 80/(4/3)
radius^3 = 60

radius = cube root (60)

Answer 8

i thought it would be v =4/3 pi(3.93)^3 = v = 4/3 pi(60.7), v = 60.7 x4/3 = 80pi

Answer 9

@triciaal @jim_thompson5910 please help is that the correct way to do it

Answer 10

r is unknown for now
v = 80pi is the given volume

Answer 11

v =4/3 pi(3.93)^3 = v = 4/3 pi(60.7), v = 60.7 x4/3 = 80pi
would r =3.93

Answer 12

\[\Large V = \frac{4}{3}\pi*r^3\]
\[\Large 80\pi = \frac{4}{3}\pi*r^3\]
\[\Large 80 = \frac{4}{3}*r^3\]
\[\Large \frac{3}{4}*80 = \frac{3}{4}*\frac{4}{3}*r^3\]
\[\Large 60 = r^3\]
\[\Large r^3 = 60\]
\[\Large r = \sqrt[3]{60} = 60^{1/3} \approx 3.91486764116887\]

Answer 13

use
\[\Large r \approx 3.91486764116887\]
to find the surface area

Answer 14

v = 4/3 pi *r^3
v = 4/3 pi*3.9^3
v = 4/3 pi*59.96
v = 4/3*59.96*pi
v =79.95 pi

Answer 15

you're using the wrong formula

Answer 16

Surface area of sphere
\[\Large SA = 4\pi*r^2\]

Answer 17

@jim_thompson5910 person did the volume you did the area

Answer 18

S.A = 4p i*3.9^2
S.A = 4 pi*59.319

Answer 19

how would i do the rest

Answer 20

check your calculation for r^2

Answer 21

3.9^2 does not turn into 59.319

Answer 22

sorry i put three instead of two

Answer 23

15.21 = 15.21 x 4 = 60.84

Answer 24

so the approx surface area is 60.84pi = 60.84*3.14 = 191.0376

Answer 25

rounding that to the nearest whole number gives 191 square cm

Answer 26

okay thank u

Answer 27

you're welcome