Question

(20 POINTS!!) Find the probability that a multiple of 3 or an odd number is rolled on a number cube.

Answer 1

1/8

Explanation:

A “standard number cube” has six sides, marked 1 2 3 4 5 and 6. Of those, exactly half are even and exactly half are odd, so we can dispense with the 6 part and just go 1/2 (the same as 3/6, after all)

So the first roll is even half the time. If it is, the second roll is odd half the time, so the chances of an even then odd pair are 1/2*1/2=1/4.

If those two happen in the correct order, the chances of the third roll being even are again 1/2… so we have 1/2*1/2*1/2=1/8

Hope it helps