mat2378-assignment3-with_sol

Mat2378-assignment3- - Assignment 3 Due date 21 October 2009 Total number of points 32 Q 1 A medical research team wished to evaluate a proposed

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Assignment 3 Due date: 21 October 2009 Total number of points: 32 Q 1. A medical research team wished to evaluate a proposed screening test for Alzheimer’s disease. The test was given to a random sample of 450 patients with Alzheimer’s disease, in 436 cases the test result was positive. Also, the test was given to a random sample of 500 patients without the disease, only in 5 cases the result was positive. It is known that in the US 11.3% of the population aged 65 and over have Alzheimer’s disease. Find the probability that a person has the disease given that the test was positive. Solution to Q1: A- test positive, D- a person has disease. Given: P ( A | D ) = 436 450 , P ( A | D c ) = 5 500 , P ( D ) = 0 . 113. To find: P ( D | A ) P ( D | A ) = P ( A and D ) P ( A ) We have P ( A and D ) = P ( A | D ) P ( D ) = 436 450 . 113 = 0 . 1094844 Compute first P ( A ) = P ( A | D ) P ( D ) + P ( A | D c ) P ( D c ) = 436 450 . 113 + 5 500 (1- . 113) = 0 . 1183544 The final answer is P ( D | A ) = 0 . 925 Marking scheme for Q1: Total - 2 points Q 2. (3.43) A certain drug causes kidney damage in 1% of patients. Suppose the drug is to be tested on 50 patients. Find the probability that (a) none of the patients will experience kidney damage; (b) one or more of the patients will experience kidney damage....
View Full Document

This document was uploaded on 01/25/2011.

Page1 / 4

Mat2378-assignment3- - Assignment 3 Due date 21 October 2009 Total number of points 32 Q 1 A medical research team wished to evaluate a proposed

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online