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Compare queueing systems and common distributions

Last updated: Mar 29, 2026

Quick Overview

This question evaluates proficiency in queueing theory, probability distributions, descriptive statistics, and interpretation of real-world data patterns such as waiting-time variability and network degree distributions.

  • medium
  • LinkedIn
  • Statistics & Math
  • Data Scientist

Compare queueing systems and common distributions

Company: LinkedIn

Role: Data Scientist

Category: Statistics & Math

Difficulty: medium

Interview Round: Technical Screen

You are asked several statistics fundamentals questions in a data science interview: 1. A bank can be organized in one of two ways: - **System A:** 5 tellers share **one common queue**. - **System B:** 5 tellers each have **their own separate queue**. Assume customer arrivals are random, tellers have similar but not identical service speeds, and some customers take much longer than others. As a customer, which system would you prefer and why? Compare the systems in terms of expected waiting time, variance of waiting time, and fairness. 2. Sketch or describe the distribution of **adult male heights in the United States** and the distribution of **adult female heights in the United States**. 3. If you pool men and women together and ignore sex, what does the **combined height distribution** look like? 4. On a social network such as LinkedIn, describe the distribution of **number of connections per user**. 5. For that connections distribution, how would **mean, median, and mode** compare, and why? If asked for the likely scale of the mean, what factors would determine it?

Quick Answer: This question evaluates proficiency in queueing theory, probability distributions, descriptive statistics, and interpretation of real-world data patterns such as waiting-time variability and network degree distributions.

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LinkedIn
Jul 8, 2025, 12:00 AM
Data Scientist
Technical Screen
Statistics & Math
2
0

You are asked several statistics fundamentals questions in a data science interview:

  1. A bank can be organized in one of two ways:
    • System A: 5 tellers share one common queue .
    • System B: 5 tellers each have their own separate queue .
    Assume customer arrivals are random, tellers have similar but not identical service speeds, and some customers take much longer than others. As a customer, which system would you prefer and why? Compare the systems in terms of expected waiting time, variance of waiting time, and fairness.
  2. Sketch or describe the distribution of adult male heights in the United States and the distribution of adult female heights in the United States .
  3. If you pool men and women together and ignore sex, what does the combined height distribution look like?
  4. On a social network such as LinkedIn, describe the distribution of number of connections per user .
  5. For that connections distribution, how would mean, median, and mode compare, and why? If asked for the likely scale of the mean, what factors would determine it?

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