Homework 2 Solutions

# Homework 2 Solutions - HW 2 SOLUTIONS 1 3.11 Suppose that a...

This preview shows pages 1–3. Sign up to view the full content.

HW 2 SOLUTIONS 1. 3.11. Suppose that a medical test has a 92% chance of detecting a disease if the person has it (i.e. 92% sensitivity) and a 94% chance of correctly indicating that the disease is absent if the person really does not have the disease (i.e. 94% specificity). Suppose that 10% of the population has the disease. What is the probability that a randomly chosen person will test positive? Correct: What is the probability of having the disease given a positive test? Correct: By the definition of conditional probability ±²³´µ¶·¸¹µ³¹µº»µ¹»¶¼½¹¸»¸´µ¾¿¶ ±²³´µ¶·¸¹µ³¹µ¶ À »µ¹»¶¼½¹¸»¸´µ¾ ±»µ¹»¶¼½¹¸»¸´µ¾ ¿ ÁÂÃ Ä ÁÂÅÆ ÁÂÃÇÈ ¿ ÁÂÈÉ 2. 3.13. The following data table is taken from a study of the relationship between health risk and income using a large group of people living in Massachusetts. Here "stressed" means the person reported that most days are extremely stressful or quite stressful; "not stressed" means that the person reported that most days are a bit stressful, not very stressful, or not at all stressful. Low Medium High Total Stressed 526 274 216 1016 Not Stressed 1954 1680 1899 5533 Total 2480 1954 2115 6549

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Use the table to answer the following questions. a. What is the probability that someone in this study is stressed? Correct: 1016 / 6549 = 0.155 b. What is the probability that someone is stressed and has low income? Correct:
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 4

Homework 2 Solutions - HW 2 SOLUTIONS 1 3.11 Suppose that a...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online