Answer:
13/21. that is 0.619
Explanation:
there are 17 + 4 + 5 + 16 = 42 things in total.
p = probabililty.
p(blue object) = (17 + 4)/ 42
= 1/2.
p(cube) = (17 + 5) /42
= 11/21.
we have to subtract the things that are both blue and a cube:
there are 17 of those. that is p(blue and cube) = 17/42.
so our answer is (1/2) + (11/21) - (17/42)
= 13/21. that is 0.619