There are $N$ rows :$R_1, R_2,R_3,..., R_N$. What is the probability of not picking a row in a random draw?
My try and understanding :
Let $X$ be a random variable which is defined as follows:
$$X = \text{ Number of rows picked in a random draw.}$$
So, the values of random variable which it can take are :
$$X = 0, 1,2,3,4,...N$$
Hence the required probability is :
$$
\begin{aligned}
\text{ Probability of not picking a row in a random draw } & = 1-\text{Probability of picking a row in a random draw } \\
& = 1 - P(X = 1) \\
& = 1 - \frac{N}{2^N}
\end{aligned}
$$
The size of sample space is $|S| = 2^N$ and the favourable outcomes are $N$ for $X =1$
Could someone explain whats wrong in it, because I read a blog on the medium* where it is mentioned the required probability is $\frac{N-1}{N}$. Follow the mentioned link or see the below screen shot:
Note: Please try to open the website in incognito mode to get rid from sign in etc and the probability thing is mentioned at the end of the blog.