probability question

[suited aces]

How to arrive a 50% probability.
For example... there are 200 balls that can be drawn from a lottery type of machine, they are either black or red.
5 balls are drawn they are all red.
What is the number of red balls needed out of the 200 to make this a outcome a 50% probability?

 

[Harry_the_cat]

Let x be the number of red balls. Can you write an expression for the probability of drawing 5 red balls in 5 draws?

 

[suited aces]

That is the question I'm asking

 

[Harry_the_cat]

Ok, let's take a step back.
Suppose there are 80 red balls out of the 200, can you calculate the probability of drawing 5 red balls in 5 draws?