# Can You Solve The Alien Extinction Riddle? Hard Job Interview Question

## Description

A single alien lands on Earth. Every day after that, each alien on Earth undergoes a transformation, which could be any of the four equally likely events: (a) the alien dies, (b) the alien does nothing, (c) the alien replicates itself (2 aliens total), (d) the alien replicates itself twice (3 aliens total). With bad luck the alien race might die out quickly. But with good luck the alien race might survive indefinitely. What is the probability the alien race eventually dies out and goes extinct? This video presents a solution to this problem, which has been asked as a technical job interview question.

Blog post: http://wp.me/p6aMk-4Sm

This puzzle was emailed to me by Anand Gautam. It has been asked as a job interview question in technical jobs.

Math StackExchange

http://math.stackexchange.com/questions/1044959/probability-and-recurrence

Analytics Vidhya (See problem 10, also includes a proof)

https://www.analyticsvidhya.com/blog/2016/07/20-challenging-job-interview-puzzles-which-every-analyst-solve-atleast/

Branching process (statistics) Wikipedia

https://en.wikipedia.org/wiki/Branching_process

Math notes on branching (more technical)

https://www.math.ucdavis.edu/~gravner/MAT135B/materials/ch14.pdf

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