A researcher is studying life expectancy in different parts of the world using birth and death records she randomly selects a sample of 20 people from town A and a samle of 20 people form town B and records their lifespans in years. Mean Lifespan in Years Standard Deviation
Town A 78.5 11.2
Town B 74.4 12.3
The researhers wants to test the claim that there is a significant differnce in lifepan for people in the two towns. What are the null and alternative hypotheses that should be used to test this claim?
a. null: mu1 - mu2 is not equal to 0; alternative: mu1 - mu2 > 0 < A
b. null: mu1 - mu2 = 0; alternative: p1 - p2 is not equal to 0 < B
c. null: mu1 - mu2 = 0; alternative: mu1 - mu2 is not equal to 0 < C
d. null: p1 - p2 = 0; alternative: p1 - p2 < 0 < D