Officials at the U.S. Environmental Protection Agency worked with hospital physicians in Anaheim, California, to examine the relationship between environmental pollution and illness. A random sample...

Officials at the U.S. Environmental Protection Agency worked with hospital physicians in Anaheim, California, to examine the relationship between environmental pollution and illness. A random sample of summer days was selected, and at 2:00 p.m. on each day the air quality was assessed by measuring the concentration of carbon monoxide (x, in ppm). Illness was measured by counting the number of new patients (y) seen for respiratory problems at the hospital that day. Suppose the true regression

An economist believes that a credit card company sets the spending limits for customers based on loyalty, that is, the number of years the customer has been a cardholder. A random sample of 22 cardholders was selected. The number of years since obtaining the card (x) was recorded as well as the spending limit (y, in thousands of dollars) on the card. The summary statistics are given below.

a. Find the estimated regression line.

b. Estimate the true mean spending limit for a customer who has had this credit card for ten years.

 c. Find an estimate of an observed value of the spending limit for a customer who has had this credit card for two years.