What is the probability that the ball lands on a number that is not on black?

Question

Roulette is a game played in many casinos in which a wheel containing numbers of various colors is spun. A ball is dropped and eventually lands on a number. What is the probability that the ball lands not on black​?

The probability that the ball lands on a number that is not on black is

​(Type an integer or a simplified​ fraction.)

Answer 1

Hi Teana.

The probability of NOT BLACK is calculated as (the number of not black slots)/(the total number of slots)

This is an easy problem made impossible because it doesn't include a description of the roulette wheel.

(Or was it you who didn't include it?)

Don't worry I'll find one on the internet.

I'll be right back.

I'm back, with interesting news.

I just discovered something about roulette wheels that I didn't know before.

They're not all the same. I found 3 different roulette wheels, but they're all pretty close.

They ALL include the numbers 1 through 36 on alternating red and black slots.

So, ALL roulette tables have 18 red slots and 18 black slots.

On this wheel the probability of red (not black) is 1:2 (50%)

Some wheels have a single GREEN slot numbered "0". This brings the total number of slots up to 37.

On this wheel the probability of red or green (not black) is 19:37 (51.35%)

Some wheels have two GREEN slots numbered "0" & "00". This brings the total number of slots up to 38.

On this wheel the probability of red or green (not black) is 20:38.

This reduces to 10:19 (52.63%)

There we go, the correct answer is it depends on the wheel.

I hope this helps.

And thank you for helping me learn something new.