Calculate Expected Users Linking Coinbase Wallets
Company: Coinbase
Role: Data Scientist
Category: Statistics & Math
Difficulty: easy
Interview Round: Technical Screen
##### Scenario
For n users independently asked to link a Coinbase wallet, each links with probability p.
##### Question
What is the expected number of users who link their wallet? What is the probability that at least one user links a wallet? Given that at least one of users A or B links a wallet, what is the probability that both A and B link?
##### Hints
Use linearity of expectation and independence: E[X]=np; P(at least one)=1−(1−p)^n; apply conditional probability for the final part.
Quick Answer: This question evaluates competence with Bernoulli trials, binomial distributions, and expectation/probability calculations relevant to modeling independent user actions such as linking a digital wallet.