Calculate Expected Links and Conditional Probability for Users
Company: Coinbase
Role: Data Scientist
Category: Statistics & Math
Difficulty: easy
Interview Round: Technical Screen
##### Scenario
Users are prompted to link their Coinbase wallet; each user independently links with probability p.
##### Question
Given n independent users with link probability p:
1) What is the expected number who link?
2) What is the probability at least one user links?
3) For two users A and B, what is the probability both link conditioned on at least one of them linking?
##### Hints
Use linearity of expectation; at-least-one equals 1−(1−p)^n; conditional P(A∩B | A∪B) = p^2 /(2p−p^
2).
Quick Answer: This question evaluates understanding of basic probability concepts including expectations for independent Bernoulli trials, event probabilities, and conditional probability in a finite user population, and falls under the Statistics & Math domain.