Math problem with circles?

Here's the question: The bull's-eye of the dartboard shown (in the link, it's red) has a diameter of 10cm. The width of each ring is 5 cm. If a random toss hits the target, what is the probability that it hits the bull's-eye?

Here's a picture of what the dart board kind of looks like (it's 3 ringed)

http://www.google.com/imgres?q=3+ring+dartboard&st...

3 Answers

Relevance
  • jsjs
    Lv 5
    9 years ago
    Favorite Answer

    The dartboard has a radius of 15 cm, so its area is Pi * (15 cm)^2.

    The bull's-eye has a radius of 5 cm, so its area is Pi * (5 cm)^2.

    Hence the probability is

    [Pi * (5 cm)^2]/[Pi * (15 cm)^2.] = (5/15)^2 = (1/3)^2 = 1/9.

  • The entire dartboard has a radius of 15cm. So, find the ratio of the area of the bullseye compared to the radius of the dartboard

    (pi * 5^2) / (pi * 15^2) =>

    25 / 225 =>

    1/9

    1-in-9

  • 9 years ago

    The radius of the target is 15 cm

    The radius of the bull's eye is 5 cm

    The area of the entire target is 9 times the area of the bull's eye

    The area of the target excluding the bull's eye is therefore 8 times the area of the Bull's eye

    If a random toss hits the target, the probability that it hits the bull's-eye is:

    1/9=0.111...

    The odds are 8 to 1 that the random hit of the target will miss the bull's eye

    .

Still have questions? Get your answers by asking now.