If a circle has a circumference of 81 pi what is its radius and area?

r = 40.5

A = 1640.25 pi

Step-by-step explanation:

The circumference is given by

C = pi *d

81 pi = pi *d

Divide each side by pi

81 = d

We can find the radius

d = 2r

81 = 2r

Divide each side by 2

81/2 = r

40.5

Now we can find the area

A = pi r^2

A = pi ( 40.5)^2

A =1640.25 pi

1. sometimes

2.   never

3   .08c = 7.50+.05c   250 pages

step-by-step explanation:

1.   sometimes

the theoretical probability of rolling a 1 is 1/6.   perhaps you got really lucky and never rolled a 1   in those 60 times.   your experimental probability is 0.   or perhaps you rolled a 1   20 times.   your experimental probability is 20/60 is 1/3.     it really just depends on how you rolled in that experiment.

2.   never

the probability of the event occurring is 1.   that is being 100 % sure it will happen.   that is the maximum amount of confidence we have.

3.   no customer card cost:   .08 times number of pages

customer card cost:   7.50 + .05 times number of pages

we want to find when it costs the same amount, so we will set these equal

let c = number of pages

.08c = 7.50+.05c

subtract .05c from each side

.08c-.05c = 7.5+.05c-.05c

.03c=7.5

divide each side by .03

.03c/.03 = 7.5/03

c =250  

the cost is the same at 250 pages