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Determine Probability of Both Children Being Boys

Last updated: Mar 29, 2026

Quick Overview

This question evaluates understanding of conditional probability, probabilistic reasoning, and the role of underlying assumptions when enumerating sample spaces, which are core competencies for data scientists.

  • medium
  • Amazon
  • Statistics & Math
  • Data Scientist

Determine Probability of Both Children Being Boys

Company: Amazon

Role: Data Scientist

Category: Statistics & Math

Difficulty: medium

Interview Round: Technical Screen

##### Scenario Interviewers test probability intuition with classic family problems. ##### Question In a family with two children, at least one is a boy. What is the probability that both are boys? State assumptions clearly. ##### Hints Enumerate the equally likely combinations BB, BG, GB, GG and condition on the given information.

Quick Answer: This question evaluates understanding of conditional probability, probabilistic reasoning, and the role of underlying assumptions when enumerating sample spaces, which are core competencies for data scientists.

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Amazon
Jul 12, 2025, 6:59 PM
Data Scientist
Technical Screen
Statistics & Math
20
0

Probability: Two-Child Family

Context

You are considering families with exactly two children. A statement is revealed: "At least one of the children is a boy." Determine the probability that both children are boys. Clearly state any assumptions you make.

Question

What is P(both children are boys | at least one child is a boy)?

Hint:

  • Enumerate the equally likely ordered outcomes: BB, BG, GB, GG.
  • Condition on the information "at least one is a boy."

Solution

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