QUESTION 37

1. A researcher from the crop and soil sciences department at your local university is interested in the relationship between the amount of phosphorus and nitrogen found in the ground. She takes a random sample of sites in the Commonwealth of Virginia and fits a linear regression model to the data. Based on this model, she obtains the following prediction results:

Nitrogen Level

Predicted Phosphorus Level

Std Error Predict

95.0% CI

95.0% PI

20

15

1.25

(12, 18)

(10, 20)

2. Suppose we wish to predict the phosphorus level of a particular site that had a nitrogen level of 20. What is a 95% interval for the prediction for this site?

(12, 18)

(10, 20)

15 1.25

15 2.49