Thread: combined events and conditional probability

When a roulette wheel is spun, the score will be a number from 0 to 36 inclusive. Each score is equally likely. Find the probability that the score is
a) an even number
b) A multiple of 3
c) a multiple of 6
d) an odd number which is not a multiple of 3

I can do a, b, and c, but for d, is there a mathematical way to do it? I took a less mathematical approach and I just wrote out all the numbers from 0 to 36 and counted which numbers were odd and not a multiple of 3.

Originally Posted by bhuang

When a roulette wheel is spun, the score will be a number from 0 to 36 inclusive. Each score is equally likely. Find the probability that the score is
a) an even number
b) A multiple of 3
c) a multiple of 6
d) an odd number which is not a multiple of 3

I can do a, b, and c, but for d, is there a mathematical way to do it? I took a less mathematical approach and I just wrote out all the numbers from 0 to 36 and counted which numbers were odd and not a multiple of 3.

Odd numbers on the wheel not multiples of 3 are 1, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35. That is there are 12 such numbers.

CB