# Some basic probability dilemma

So I started studying probability and while it seemed all ok I'm having trouble wrapping my head around this one. So the question is: We have 100 balls , 10 black and 90 white. In 50 tries what is the probability of getting 0 to 10 black balls? Now I need to get probability for excels BINOM.DIST function and am having dilemma. Do we need to calculate 1 black divided by total black (10) or getting 10 black out of 100 total? I get 0.1 for both cases and that makes this bit more confusing.

• if this is HW please add the self-study tag – Antoine May 22 '16 at 18:26
• Your question is vaguely worded: could you please be more specific? After all, it's obvious that you must get somewhere between 0 and 10 black balls in 50 tries, making the probability 100%. That's so trivial, though, I would guess you really want to compute eleven separate probabilities: the chance of getting exactly zero black balls in 50 "tries," the chance of getting exactly one black ball in 50 "tries," etc. That brings up another ambiguity: what exactly is a "try"? It sounds like it would be observing the color of a single randomly drawn ball and then replacing it. Is this so? – whuber May 22 '16 at 22:55