Refer to the simple linear regression of sweetness index y and amount of pectin x for n = 24 orange juice samples, Exercise 9.14 (p. 484).A 90% confidence interval for the mean sweetness index, E(y), for each value of x is shown on the SPSS spreadsheet on page 526. Select an observation and interpret this interval.
Exercise 9.14
The quality of the orange juice produced by a manufacturer (e.g., Minute Maid,Tropicana) is constantly monitored. There are numerous sensory and chemical components that combine to make the best tasting orange juice. For example, one manufacturer has developed a quantitative index of the "sweetness" of orange juice. (The higher the index, the sweeter the juice.) Is there a relationship between the sweetness index and a chemical measure such as the amount of water soluble pectin (parts per million) in the orange juice? Data collected on these two variables for 24 production runs at a juice manufacturing plant are shown in the table. Suppose a manufacturer wants to use simple linear regression to predict the sweetness (y) from the amount of pectin (x).
a. Find the least squares line for the data
b. Interpret 
, and 
in the words of the problem.
c. Predict the sweetness index if amount of pectin in the orange juice is 300 ppm
