Here is an interview question of hypothesis test:
When you observe 10% more heads than tail, how many times do you have to test to get the statistical significance to say coin is biased?
I don't much understand what I should test?
Does that mean we should test $H_0: p = 50\%,$ using number of head $X\sim N(np,np(1-p))?$ And calculate $n$ to make $$\dfrac{55\%n-np}{\sqrt{np(1-p)}}$$ match significant level? Here $55\% - 45\% = 10\%.$
