Question: Efficiency experts with a manufacturing firm wish to study the relationship between the time required for an employee to complete a certain task and the light intensity and noise level at the workstation. Their data on 20 employees are presented in the following table.

Time Required Light Noise To complete task intensity level 58 5 58
90 8 70
60 7 65
45 4 54
125 11 83
100 9 72
115 10 76
52 6 59
85 8 68
135 10 60
125 11 81
40 5 59
95 9 71
70 6 62
120 10 75
86 7 64
80 7 66
65 6 61
95 8 66
25 5 57

a. Find the multiple regression equation describing the relationship among these variables.

b. Compute R².

c. Let X₁ = 10 and X₂ = 60 and find the predicted value of Y.