Question

Please help me!!!!
1. a dartboard consists of two concentric circles the probability of hitting the inner circle is 64% it the outer circle has a diameter of 20 inches what is the radius of the inner cirlce?
A. 2 inches
B. 4 inches
C. 8 inches
D. 16 inches
2. using a sixteen-sided number cube what is the probability that you will roll an even number of an odd prime number? the number 1 isnt an odd prime. round to three decimals.
A. 0.063
B. 0.813
C. 0.219
D. 0.156

Answer 1

1)
area of outer circle =3.14*400
64% of this area is the area of smaller circle.
x / 3.14*400 * 100 =64
x=803.16
area of smaller circle = 3.14 *r^2 = 803.16
r^2 = 256
r = 16

Answer 2

oh okay i get that thank you, i just really need help with # 2