7 quant interview questions (+ answers to expect)

Hiring talented quantitative analysts (quants) can be a challenge for many organizations. The specialized skills required for this role, such as math, statistics, and programming, can lead to candidate shortages and create fierce competition between companies striving to secure top talent from a limited candidate pool. 

To secure skilled employees for your organization, it’s crucial to adequately assess candidates and avoid the costly mistakes of mis-hiring, such as wasted resources, reduced productivity, and impacted revenue.

In this guide, we provide seven novel quant interview questions with responses to look for that you can implement into your hiring process. 

Get to know your quant candidates

Before diving into the more technical quant interview questions, it’s important for recruiters and hiring managers to have an understanding of their candidates, such as how they think and what motivates them.

For example, inquiring about the most enjoyable aspect of working in quantitative analysis helps uncover candidates' specific passions within the field, providing insight into their genuine interests. 

Look for responses that connect their professional motivations to the organization's growth, such as their enjoyment of mathematical problem-solving, appreciation for quantitative precision, and ability to thrive in collaborative environments.

Seven interview questions and answers for quantitative analysts

Learn a thing or two from the following examples of quant interview questions:

1. You have two ropes. Each rope takes exactly one hour to burn from one end to the other. These ropes don’t burn at a consistent rate, meaning one end might burn faster than the other. How can you measure exactly 45 minutes using only these two ropes and a way to light them? 

This question helps recruiters assess candidates' problem-solving skills, logical thinking, and ability to apply mathematical concepts in a real-world scenario.

It tests their capacity to devise innovative solutions and adapt to unconventional situations. These are valuable qualities in quantitative roles where complex problems often come up. 

The response to look for: 

1. Ignite both ends of the first rope and one end of the second rope at the same time.

2. Let the first rope burn for 30 minutes, as it will burn entirely from one end to the other.

3. While the first rope is burning for 30 minutes, the ignited end of the second rope will burn for 15 minutes.

4. After 30 minutes, the first rope will have finished burning. At this point, ignite the other end of the second rope.

5. The second rope still has 15 minutes left to burn, but now it will take exactly 15 minutes for it to burn from the new end to the other end.

6. When the second rope is completely burned, precisely 45 minutes will have passed since you started both ropes.

2. You're analyzing data about students' test scores. How would you use a statistical model to predict a student's future test score based on their past performance?

This question determines whether candidates understand how to use data and math to make predictions. It tests their ability to choose the right model, analyze information, and see patterns in data. Quants often use this practical skill in finance to predict future prices and make data-backed decisions.

To predict a student's future test score using a statistical model, follow these steps:

1. Data collection: Gather information about the student's past test scores, including other factors that could affect their performance, like study time, sleep, and stress levels.

2. Select a model: Choose a statistical model, like linear regression, which provides straightforward insights into how past test scores and other variables affect future scores. It’s a baseline model to determine whether a linear relationship adequately explains the data, before considering more complex alternatives. 

3. Analyze data: Input the student’s past test scores and study habits into the model to find a clear mathematical relationship between past test scores and future scores. By examining the coefficients of these input features, the model reveals how each factor contributes to predicting student performance.

4. Make predictions: Once the model is ready, plug in a student's past data and the other variables to predict their future test score.

5. Evaluate accuracy: Check how accurate the predictions are by comparing them to actual test scores. If the predictions are close, the model is doing a good job.

3. Explain how you would create a computer program to help decide when to buy or sell stocks based on certain rules or patterns you've observed in the stock market.

Quants need to know how to use coding and logic to make decisions in a fast-moving financial world. This question assesses candidates’ ability to turn their trading ideas into a computer program and their understanding of risk management – a crucial aspect of trading.

Candidate responses should touch on the following key aspects: 

• Algorithm design: This is the process involved in designing the trading algorithm, including the rules, patterns, or strategies they've developed for buying and selling stocks. 

• Data analysis: This includes identifying and validating trading patterns by collecting historical stock market data, cleaning and reprocessing it, and conducting statistical analysis to confirm the patterns’ reliability. 

• Programming languages: Determine the languages and tools that would be used to implement the trading algorithm, such as Python, R, or specialized trading platforms. 

• Risk management: This includes measures such as stop-loss orders, position sizing, or portfolio diversification to mitigate potential losses.

4. Describe how you would clean and organize a large dataset of weather data to analyze temperature changes over the past year. 

It’s common in many data-driven jobs to be able to handle and clean inconsistent, or disorganized data. This question assesses whether your quant candidates can organize data for analysis, which is vital for making accurate predictions and decisions.

A strong candidate response should touch on the following three key aspects: 

1. Data preprocessing techniques: These are the specific techniques used to clean and organize the large dataset, like handling missing data, outlier detection and treatment, data normalization, and the removal of duplicates. 

2. Time series handling: This is the handling of date and time information within the dataset – regarding temperature analysis, specifically. This may involve parsing and converting timestamps, aggregating data into meaningful time intervals (e.g. daily or monthly averages), and identifying trends in the temperature data.

3. Data storage and optimization: This includes using data storage formats like CSV, SQL databases, or specialized time series databases, and data structuring techniques, to efficiently retrieve and analyze temperature data over the past year. 

5. Explain the Black-Scholes mathematical model and its practical applications. 

The Black-Scholes model is a fundamental financial model that most quants should be familiar with. This question is a great way to assess quants’ understanding of the model and its real-world applications. 

The response to look for: 

The Black-Scholes model is a mathematical formula used in finance to: 

• Decide the cost of financial instruments, like stock options, futures contracts, and other derivatives.

• Model financial market dynamics using advanced mathematical concepts, considering variables like current asset price, option strike price, and implied volatility.

6. Explain how stress testing is applied in the field of cybersecurity to assess the resilience of a computer network and protect it from potential threats.

This question evaluates candidates’ understanding of how stress testing is applied in a specific quantitative context, such as cybersecurity. 

It tests their ability to use quantitative methods to identify vulnerabilities and weaknesses in a complex system, which is crucial in both finance and cybersecurity.

Candidates’ responses should explain how stress testing in cybersecurity involves deliberately subjecting a computer network to simulated cyberattacks or excessive traffic to evaluate how well it can withstand certain pressures.

They should also mention how security experts can identify vulnerabilities, weaknesses, and potential points of failure within the network's defenses through stress testing. 

Finally, candidates should specify how the insights gained from this process help organizations strengthen their security measures, enhance incident response plans, and better protect their networks from real-world threats.

7. You have a bag with 10 marbles: five red, three green, and two blue. If you draw two marbles without replacement, what's the probability you'll get one red marble and one green marble?

This question requires candidates to apply intermediate-level probability concepts in a practical scenario. It’s a valuable assessment tool because it tests their ability to calculate probabilities involving multiple events without replacement – a key skill in quantitative analysis.

To calculate this probability, think of it as two separate events: 

Event 1: A red marble is drawn on the first try. The chance of this happening is five red marbles out of the ten total marbles in the bag, which is 5/10 or ½.

Event 2: On the second try, a green marble is drawn. After already removing one marble from the bag, there are only nine marbles left. Of those nine, three are green. So, the probability of picking a green marble on the second try is 3/9 or ⅓. 

To find the overall probability of both events happening in sequence, multiply their individual probabilities: 

½ x ⅓ = ⅙ 

Therefore, there’s a ⅙ chance of picking one red and one green marble when you draw two marbles from the bag without replacement. 

How to assess a candidate’s quant skills

Novel interview questions are a great way to assess an applicant’s skills, but they shouldn’t be used as the sole basis for decision-making. 

For a comprehensive assessment of your quant candidate, consider taking TestGorilla’s multi-measure approach, combining role-specific skills tests, cognitive ability tests, and personality assessments with quant interview questions.

Mix and match tests from TestGorilla’s extensive library of 300-plus tests to create a tailored assessment.

• Mathematical and statistical skills tests evaluate candidates’ overall numerical aptitude and ability to interpret numbers in various practical contexts. 

• Programming skills tests assess candidates’ practical experience with coding languages and working with arrays. 

• Data analysis tests evaluate how candidates understand and statistically interpret data to make decisions. 

• Communication skills tests measure candidates’ abilities to communicate professionally with clarity and effectiveness, considering written and spoken communication, as well as active listening skills.   

• Problem-solving skills tests look at candidates’ capacity to define problems, analyze data, and process textual information to make accurate decisions. 

• Attention to detail tests assess candidates’ ability to focus on textual details while processing information.

Take a multi-measure approach to recruit skilled quants 

Quantitative analysts are highly skilled professionals who have a range of expertise in math, statistics, and programming.

Finding the right quant for your business can be challenging, so it’s important to use all the tools you have. First, draw in strong applicants with an effective quantitative analyst job description. Then, assess the most-promising candidates to determine if they can handle your sensitive and complex data.

Quant interview questions are a vital part of the hiring process because they require candidates to show their technical, cognitive, and interpersonal skills in real time. 

However, for best results, HR managers should consider taking a multi-measure approach to hiring and combine these questions with skills-based assessments to obtain a comprehensive profile of a candidate.

Want more tools to recruit quantitative analysts? Sign up for TestGorilla’s Free plan or request a free 30-minute live demo today.