5. Quantitative Reasoning
Probability Basics — Quiz
Test your understanding of probability basics with 5 practice questions.
Practice Questions
Question 1
A rare disease affects $0.1\%$ of the population. A diagnostic test for this disease has a sensitivity (true positive rate) of $99\%$ and a specificity (true negative rate) of $95\%$. If a randomly selected person tests positive for the disease, what is the probability that they actually have the disease?
Question 2
A company manufactures electronic components. It is known that $2\%$ of the components produced are defective. A quality control test for these components has a true positive rate of $98\%$ and a false positive rate of $5\%$. If a randomly selected component tests positive, what is the probability that it is actually defective?
Question 3
In a city, $60\%$ of adults own a smartphone, $40\%$ own a laptop, and $25\%$ own both. What is the probability that a randomly selected adult owns a smartphone or a laptop?
Question 4
A factory has two machines, A and B, that produce a certain item. Machine A produces $70\%$ of the items, and Machine B produces $30\%$ of the items. It is known that $3\%$ of the items produced by Machine A are defective, and $5\%$ of the items produced by Machine B are defective. If an item is randomly selected and found to be defective, what is the probability that it was produced by Machine B?
Question 5
A fair six-sided die is rolled three times. What is the probability of getting at least one '6'?