Retail Price Data for N = 60 Hard Disk Drives $y =$

Multiple Choice

Retail price data for n = 60 hard disk drives were recently reported in a computer magazine. Three variables were recorded for each hard disk drive: $y =$ Retail PRICE (measured in dollars)
$x _ { 1 } =$ Microprocessor SPEED (measured in megahertz)
(Values in sample range from 10 to 40 )
$x _ { 2 } =$ CHIP size (measured in computer processing units)
(Values in sample range from 286 to 486 )
A first-order regression model was fit to the data. Part of the printout follows:





Identify and interpret the estimate for the SPEED $\beta$ -coefficient, $\hat { \beta } _ { 1 }$ .

A) $\hat { \beta } _ { 1 } = 3.57$ ; For every $\$ 1$ increase in PRICE, we estimate SPPED to increase by about 4 megahertz, holding CHIP fixed.
B) $\hat { \beta } _ { 1 } = 3.57$ ; For every 1 -megahertz increase in SPEED, we estimate PRICE to increase $\$ 3,57$ , holding CHIP fixed.

C) $\hat { \beta } _ { 1 } = 105$ ; For every $\$ 1$ increase in PRICE, we estimate SPEED to increase 105 megahertz, holding CHIP fixed.
D) $\hat { \beta } 1 = 105$ ; For every 1 -megahertz increase in SPEED, we estimate PRICE (y) to increase $\$ 105$ , holding CHIP fixed.