First find the numbers that are divisible by 3.
3, 6, 9, 12, 15, 18, 21, 24
There are 8 numbers divisible by 3 so there are 16 that are not divisible by 3.
P(not div by 3) = 16/24 = 2/3
4c6d3 x 3c4d
4 x 3=12
12c
you add the powers so 6+4=10
12c10
d3 x d=d3
12c10d3
that is the answer i think
See the image below for a demonstration. Hope this helps out.
This equals the the area of white part / area of the entire dartboard
area of the entire board = pi * 6^2 = 36pi
area of white part = 36pi - 2^2*pi = 32pi
do required probability = 32pi / 36pi = 0.889 or 88.9 % (to nearest tenth)
or as a fraction it is 8/9