Question 4.33

4.33 Online health information.

Based on a random sample of 1066 adults (18 years or older), a Harris Poll (July 13–18, 2010) estimates that 175 million U.S. adults have gone online for health information. Such individuals have been labeled as “cyberchondriacs.” Cyberchondriacs in the sample were asked about the success of their online search for information about health topics. Here is the distribution of responses:11

Very
successful		 Somewhat
successful		 Neither successful
nor unsuccessful
Probability 0.41 0.45 0.04
Somewhat
unsuccessful		 Very
unsuccessful		 Decline
to answer
Probability 0.05 0.03 0.02
  1. Show that this is a legitimate probability distribution.
  2. What is the probability that a randomly chosen cyberchondriac feels that his or her search for health information was somewhat or very successful?

4.33

(a) (b) 0.86.