Subprime Mortgages The following graph shows the approximate percentage of...

Subprime Mortgages The following graph shows the approximate percentage of mortgages issued in the United States that are subprime (normally classified as risky) as well as the logistic regression curve:

a. Which of the following logistic functions best approximates the curve? (t is the number of years since the start of 2000.) Try to determine the correct model without actually computing data points. HINT [See Properties of Logistic Curves on page 166.]

b. According to the model you selected, during which year was the percentage growing fastest? HINT [See the “Before we go on” discussion after Example 1.]

Example 1:

A flu epidemic is spreading through the U.S. population. An estimated 150 million people are susceptible to this particular strain, and it is predicted that all susceptible people will eventually become infected. There are 10,000 people already infected, and the number is doubling every 2 weeks. Use a logistic function to model the number of people infected. Hence predict when, to the nearest week, 1 million people will be infected.