Question

What is the probability that Jake's throw will earn at least 30 points?

13.6%
33.5%
36%
73%

Answer 1

33.5%

Explanation:

Area of whole dartboard

radius = 3 + (4 x 4) = 19

⇒ area of whole dartboard =
`\pi`19² = 361
`\pi`

Area of 30, 40 and 50 points zone

radius = 3 + (2 x 4) = 11

⇒ area of at least 30 points =
`\pi`11² = 121
`\pi`

Probability

probability = (121
`\pi` ÷ 361
`\pi`) x 100 = 33.5%