1) I supply the 2 sample sizes

2) For sample 1, I supply a constant proportion of .50

3) I increase the proportion for sample 2 from .55 by .01 until the result is significant

Other settings:

The significance level is set to .05.

I also tell the calculator to use a two tailed hypothesis.

I looked up a formula to calculate this score by hand but I am stuck because I don't have the favorable cases to calculate each sample's proportion as well as the overall proportion. I'm not sure if I have been clear enough in my explanation because my statistics knowledge is quite limited. I have read many articles and watched youtube videos. They all seem to say that I would need the favorable cases for each sample to calculate all 3 proportions to plug into the formula. However, the online z test calculator I use does not ask for this info and still can produce an answer. Is it using a default of some sort? Here is the link to the calculator I use if that helps: https://www.socscistatistics.com/tests/ztest/default2.aspx

I apologize in advance if links are not allowed in posts.