Based on 207 students' scores on the final examination in a course ni finance, the following model was estimated by least squares. W h e r e : y i = Bo + B i x t i + B e x z i + B 3 X 3 i y; = student's actual score on the examination. x/, = hours per week spent working on the course xzi = number of hours of sleep deprivation x3; =student's grade point average The least squares estimate of the regression parameters were as folows: b0 = 7.35 b, = 3.369 62=-0.025 b3=3.054 Based on the information presented interpret the estimates bi, bz, b3