A drunkard executes a "random walk" in the following way: Each minute he takes a step north or south, with probability1/2each, and his successive step directions are independent. His step length is 50 cm. Answer this problem under the assumption that the drunkard has some idea of where he wants to go so that he steps north with probability2/3and south with probability1/3.

This problem is the number 14 of the book "Mathematical Statistics and Data Analysis of John A Rice". This book can be found at this link: https://drive.google.com/drive/folders/1vM-57ZfQBjojQ2XewlPkxqT9dLgDd5f3?usp=sharing