How do I approach Statistics & Math interview questions?

Statistics & Math questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master statistics & math interviews.

What difficulty level is this interview question?

This is a easy difficulty Statistics & Math question, commonly asked during Technical Screen rounds at LinkedIn.

What role is this question designed for?

This question is commonly asked for Data Scientist candidates at LinkedIn during technical interviews.

Choose better bank queue and describe distributions

Quick Overview

This question evaluates probabilistic reasoning and statistical intuition—queueing theory for expected waiting time and variability plus distributional reasoning for unimodal versus bimodal shapes and comparisons among mean, median, and mode—in the Statistics & Math domain for a data scientist role.

You are interviewing for a data role and are asked several probability/distribution questions.

1) Bank queue choice (queueing intuition)

A bank has 5 tellers.

Option A: 1 single line feeding the next available teller (1 queue → 5 servers).
Option B: 5 separate lines, one per teller (5 queues → 5 servers).

Question: Which option would you choose to minimize your waiting time? Explain in terms of expected waiting time and variability, and state any assumptions you need (arrival process, service-time distribution, customer behavior like line switching).

2) Sketch common real-world distributions

(a) Heights

Sketch the distribution of:

Adult men’s heights in the US
Adult women’s heights in the US
The combined distribution when you mix men and women

Describe the likely shape (e.g., unimodal/bimodal), approximate symmetry/skew, and what assumptions justify that.

(b) LinkedIn connections

Let each user have a number of connections (e.g., 100, 200, 500, …).

Sketch the distribution of number of connections per user .
Give a plausible range for the mean (order-of-magnitude is fine) and explain what data properties drive it.
For this distribution, compare mean vs. median vs. mode (which is largest?) and explain why.

Quick Overview

1) Bank queue choice (queueing intuition)

A bank has 5 tellers.

Option A: 1 single line feeding the next available teller (1 queue → 5 servers).

Option B: 5 separate lines, one per teller (5 queues → 5 servers).

2) Sketch common real-world distributions

(a) Heights

Sketch the distribution of:

Adult men’s heights in the US

Adult women’s heights in the US

The combined distribution when you mix men and women

Describe the likely shape (e.g., unimodal/bimodal), approximate symmetry/skew, and what assumptions justify that.

(b) LinkedIn connections

Let each user have a number of connections (e.g., 100, 200, 500, …).

Sketch the distribution of number of connections per user .

Give a plausible range for the mean (order-of-magnitude is fine) and explain what data properties drive it.

For this distribution, compare mean vs. median vs. mode (which is largest?) and explain why.

Choose better bank queue and describe distributions

Quick Overview

1) Bank queue choice (queueing intuition)

2) Sketch common real-world distributions

(a) Heights

(b) LinkedIn connections

Solution

Submit Your Answer to Earn 20XP

Choose better bank queue and describe distributions

Quick Overview

1) Bank queue choice (queueing intuition)

2) Sketch common real-world distributions

(a) Heights

(b) LinkedIn connections

Solution

Submit Your Answer to Earn 20XP