# Stat 330 (Spring 2015): Homework 12

```Stat 330 (Spring 2015): Homework 12
Due: May 1, 2015
the course number and the section on every sheet. Show all work to earn partial credit. Problems marked
1. * A student interested in purchasing a multifunction inkjet printer wanted to study the relationship
between the retail price (in dollars) and the printing speed (pages per minute) of a typical personal
printer. He obtained data for 20 inkjet printers from a current PC magazine and calculated the following
statistics:
n = 20
Σ x2i = 167.51
Σ xi = 56.3
Σ yi2 = 658528
Σ yi = 3232.0
Σ xi yi = 9918.3
(a) Estimate the linear regression equation predicting the price of an inkjet printer, y, based on the
printing speed, x.
(b) Predict the price in dollars for a printer with a speed of 3.5 pages a minute.
(c) Calculate the sample correlation between x and y and the coefficient of determination, R2 . What
does the R2 value tell you about the fit of your line?
(d) Provide an estimate of the error variance σ 2
2. * (Baron’s book): 9.10
3. * (Baron’s book): 9.16
1
```