4. Probability

Conditional Probability — Quiz

Test your understanding of conditional probability with 5 practice questions.

Practice Questions

Question 1

A school reports that $60\%$ of its students participate in sports (S) and $40\%$ are in the drama club (D). If $25\%$ of the students participate in both sports and drama, what is the probability that a student is in the drama club given that they participate in sports?

Question 2

A survey of 100 people found that 70 people own a smartphone (S) and 50 people own a laptop (L). 30 people own both a smartphone and a laptop. What is the probability that a randomly selected person owns a laptop given that they own a smartphone?

Question 3

A company has two departments: Sales and Marketing. $70\%$ of employees are in Sales, and $30\%$ are in Marketing. Of the employees in Sales, $80\%$ have a college degree. Of the employees in Marketing, $60\%$ have a college degree. What is the probability that a randomly selected employee has a college degree?

Question 4

In a town, $40\%$ of adults read Newspaper A, $30\%$ read Newspaper B, and $15\%$ read both. If an adult is chosen randomly and it is known that they read Newspaper B, what is the probability that they also read Newspaper A?

Question 5

A medical test for a disease has a $95\%$ true positive rate (correctly identifies diseased individuals) and a $98\%$ true negative rate (correctly identifies healthy individuals). If $1\%$ of the population has the disease, what is the probability that a person who tests positive actually has the disease?