Conditional Probability: Population Obesity and Teenage Pregnancies

1.a) Overweight? Choose an American adult at random. Define two events:

A= the person chosen is obese
B= the person chosen is overweight but not obese

According to the 2007 National Health Interview Survey, P(A)=0.26 and P(B)=0.35. Explain why events A and B are disjoint.

1. b) Say in plain language what the event "A or B" is. What is P(AorB)?

1. c) If C is the event that the person chosen has normal weight or less, what is P(C)?

2. Older Women. Government data show that 6% of the American population are at least 75 years of age and that about 52% of Americans are women. Explain why it is wrong to conclude that because (0.06)(0.52)=0.0312 about 3% of the population are women aged 75 or older.

3.a) Teenage pregnancies. The U.S. National Center for Health Statistics reports for 2006 the distribution of teenage pregnancies by age range and ethnicity of the mother.
15 to 17 years old 18 to 19 years old
White 0.22 0.49
Black 0.09 0.17
Other 0.01 0.02

Overall, what percent of teenage pregnancies are in young mothers 15 to 17 years old?

3.b) What is the conditional probability that a teenage pregnancy is in a young mother 15 to 17 years old, given that she si classified as "white"?

3.c) What is the conditional probability that a teenage pregnancy is in a young mother 15 to 17 years old, given that she is classified as "black"?