# How many red balls in jar (Negative Hypergeometric Distribution)

We have 100 balls in a jar. We take samples without replacement. How many of them have to be red so that we will have found one red ball after at most 16 tries with a probability of P>0.5 for k repeating experiments?

I have been advised to use the negative hypergeometric distribution. I can understand how it works but i am stuck at some point. For the Negative hypergeometric distribution there is:

N=100

K=C, Population of successes- red balls

F=100-C, Population of Failures

How can we calculate this? The result can be decimal.