Question

A ballon has a circumfrence of 11cm. Use the circumference to approximate the surface are of the balloon to the nearest square centimeter! Help!

a 121
b380
c39
d154

Answer 1

use this concept http://answers.yahoo.com/question/index?qid=20110715171126AAXwqEF

Answer 2

I looked at that I couldn't figure it out.

Answer 3

just plug your info to the equation that the person gave

Answer 4

Surface area is 4 pi r sq
Circumference is 2 pi r
Circumference is 23 cm
2pi r =23
r = 23 x 7/44 = 3.659 cm
Surface area = 4 pi r sq = 4 x 22/7 x 3.659 x 3.659 = 168.31
Answer : 168 sq cm.

Answer 5

where is the 7 and 44 coming from though? that is what mixed me up

Answer 6

is this ballon a perfect sphere?

Answer 7

@zacmcgraw8 ?

Answer 8

yes

Answer 9

@Jamierox4ev3r

Answer 10

oh okay then the surface area of a sphere is \[A=4\pi(r)^2\]

Answer 11

divide the diameter by 2 and you have the radius. Then plug it in to the equation

Answer 12

A=4pi(5.5)^2
A=4pi(30.25)
A=4 (94.985
A=379.94

Answer 13

if you round this to the nearest square acre, then your answer is 380 acres ^2.
This means your answer is B.

Answer 14

Does this make sense @zacmcgraw8 ?

Answer 15

Yes