Contributions: Gabriela Ramos and Pedro Gonçalves

Case interviews are known for challenging even the most seasoned candidates. However, with strategic preparation and a focus on the right concepts, you can stand out and showcase your potential in a clear and impactful way.

This article is the first in a three-part series about case interviews at Nubank! By clicking here, you’ll find the other articles in the series, along with many other valuable insights on what it’s like to be a Business Analyst at Nu!

Below, we dive into the core mathematical and financial topics that frequently come up in case interviews. Ready to get started?

1. Percentage

Percentage is a foundational mathematical tool to express proportions on a base of 100. In the business world, it’s widely used to calculate increases, discounts, profit margins, and rates of change. Its basic formula is:

[ \text{Porcentagem} = \left( \frac{\text{Parte}}{\text{Total}} \right) \times 100 ]

Watch an in-depth video on percentage here..

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2. Rule of Three

The rule of three is a key mathematical technique for solving proportional problems, split into two categories:

a. Simple Rule of Three

Used for problems where two quantities are directly or inversely proportional, allowing you to find unknown values from known variables.

[ \frac{a}{b} = \frac{c}{d} ]

Watch the video on the simple rule of three here.

[Exercises]

b. Compound Rule of Three

An extension of the simple rule, applied in situations involving three or more proportional variables.

[ \left( \frac{a}{b} \right) = \left( \frac{c}{d} \right) = \left( \frac{e}{f} \right) ]

For a deeper understanding, watch the video on the compound rule of three here.

3. Profit and Interest

These financial concepts are crucial for assessing project feasibility. Profit is derived by subtracting total cost from revenue, while interest is calculated based on a rate applied to the principal over time:

[ \text{Lucro} = \text{Receita Total} – \text{Custo Total} ] [ \text{Juros Simples} = \text{Principal} \times \text{Taxa} \times \text{Tempo} ]

To learn more about interest, click this link.

You can find exercises here.

a. Gross and Net Revenue

Gross revenue represents total sales or services before deductions, while net revenue accounts for expenses applied, resulting in the final amount.

[ \text{Receita Líquida} = \text{Receita Bruta} – \text{Descontos e Deduções} ]

Explore more about gross and net revenue here.

4. Functions

Mathematical functions are formulas that describe the relationship between variables. In case interviews, functions can be used to calculate percentages, profit, and revenue. The basic function is:

[ f(x) = y ]

5. Statistics and Probability

Essential for data analysis, statistics gathers and interprets data, while probability measures the likelihood of events.

a. Mode, Mean, and Median

Three measures of central tendency used to describe a data set.

  • Mode: the most frequent value.
  • Mean: sum of values divided by the number of data points.
  • Median: the central value in an ordered data set.

Watch the explanatory video here.

More information can be found here.

b. Quartiles

Quartiles divide an ordered data set into four equal parts, offering a more detailed view of distribution.

[ Q1, Q2, Q3, Q4 ]

Discover more about quartiles here. 

Conclusion

Preparing for a case interview requires a strong grasp of essential concepts and continuous practice. Mastering topics like percentages, rule of three, profit, interest, functions, and statistics will set you apart. Follow this guide series and deepen your knowledge to ensure exceptional performance.

And remember: this article is the first in a three-part series about case interviews. Continue your journey by clicking here and dive into content that will help you gear up for the challenges and opportunities Nubank has to offer!

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