In a PC World comparison of computer hard drives, data describing the drives included the following variables: price (dollars), disk capacity (gigabytes), and rotational speed (RPM). The data are in file XR17027. With y = price, x1 = disk capacity, and x2 = rotational speed (coded as 1 = 7200 RPM and 0 = 5400 RPM), determine the linear regression equation for estimating price as a function of the two predictor variables and interpret the partial regression coefficients. For a given storage capacity, how much extra would one expect to pay for a hard drive with the higher rotational speed?