Stats 4 Day 14b

SILENT DO NOW ON DESK: Agenda: pen/pencil Intro to Trees Notebook Practice Trees DO NOW: Tables Review ½ sheet Homework due Tuesday: Ch. 15 Conditional Prob. Worksheet 10 min

Article Problem Let’s do the problems from the article! 1. plant problem: Before going on vacation for a week, you ask your spacey friend to water your ailing plant. Without water, the plant has a 90% chance of dying. Even with proper watering, it has a 20%chance of dying, and the probability that your friend will forget to water it is 30%. (a) What’s the chance that your plant will survive the week? (b) If it’s dead when you return, what’s the chance that your friend forgot to water it? (c) If your friend forgot to water it, what’s the chance it’ll be dead when you return? 15 min

2. breast cancer problem The probability that one of these women has breast cancer is 0.8 percent. If a woman has breast cancer, the probability is 90 percent that she will have a positive mammogram. If a woman does not have breast cancer, the probability is 7 percent that she will still have a positive mammogram. Imagine a woman who has a positive mammogram. What is the probability that she actually has breast cancer?

Stats 4 Day 15b

SILENT DO NOW ON DESK: Agenda: HW Worksheet HW presentation Practice Together Group Practice(HW) DO NOW: ½ Sheet Homework due Thursday: Ch 15 Conditional Probability Packet 10 min

Practice Together 1. What is the probability her luggage arrives? Marisol is flying from Boston to Denver with a connection in Chicago. The probability her first flight leaves on time is 15%. If the flight is on time, the probability her luggage makes it on the connecting flight is 98%, but if her first flight is delayed, the probability her luggage makes it on the connecting flight is only 70%. 1. What is the probability her luggage arrives? 2. If she doesn’t get her luggage, what is the probability her first flight was delayed?

Dependent Probability A pregnancy test is 99% accurate (which means if you are pregnant, 99% of the time it will tell you that you are pregnant, 1% of the time it will tell you that you are not). However, if you are not pregnant, only 97% of the time it will be correct. If there is a 5% chance that you are actually pregnant, find the probability of actually being pregnant if the test tells you that you are.

Example A private college reports the following: 70% of incoming freshmen attended public high schools. 75% of public high school students who enroll eventually graduate from the college. 90% of freshmen from nonpublic high schools eventually graduate from the college. 1. What percent of incoming freshmen graduate? 2. What percent of those who graduate were private school students? 3. Is graduation from this college dependent on type of high school?