Assignment
1. Hypothesis Testing:
In a survey of 1005 adult Americans, 46% indicated that they were somewhat interested or very interested in having web access in their car (USA Today, May 1, 2009). Suppose that the marketing manager of a car manufacturer claims that the 46% is based only on a sample and that 46% is close to half, so there is no reason to believe that the proportion of all adult Americans who want car web access is less than 0.50. Is the marketing manager correct in his claim? Provide statistical evidence to support your answer by testing the appropriate hypotheses using a 0.05 significance level. For purpose of this exercise, assume that the sample can be considered as representative of adult Americans.
2. Population Regression:
An experiment to study the relationship between x = time spent exercising (minutes) and y = amount of oxygen consumed during the exercise period resulted in the following summary statistics.
n = 20, ∑x = 50, ∑y = 16,705, ∑x2 = 150, ∑y2 = 14,194,231, ∑xy = 44,194
a. Estimate the slop and y intercept of the population regression line.
b. One sample observation on oxygen usage was 757 for a 2-minute exercise period. What amount of oxygen consumption would you predict for this exercise period, and what is the corresponding residual?
c. Compute a 99% confidence interval for the average change in oxygen consumption associated with a 1-minute increase in exercise time. (Hint: this is about the computation of a confidence interval for β. Also, in the computation the ?? critical value based on df = 20 - 2 = 18 with confidence level 99% is 2.878).