We obtain the following results for a regression model used to assess the impact of the number of jobs per hour that request over 5 microseconds of central processor time \(\left(\mathrm{X}_{1}\right)\) and the number of jobs per hour that require more than one work space in main memory \(\left(\mathrm{X}_{2}\right)\) on the response time of a system (measured in seconds):

\[Y=.106+.371 X_{1}+.402 X_{2}\left(R^{2}=.16\right)\]

Required:

a What is the expected impact on response time of introducing two more jobs into the system that request more than 5 microseconds of processor time?

b What is the impact on response time of introducing one more job that requests more than 5 microseconds of processor time and four jobs that require more than one work space?

c What is the expected response time if there are no jobs in the system requiring more than 5 microseconds of processor time or more than one work space?

d What kinds of concerns might we have about the validity of the estimations made using this model?