A journalist for an automotive magazine wants to determine how the weight of a passenger vehicle, in kilograms, is related to its length, in centimeters; the maximum number of passengers; and its safety rating on a 5-point scale. What is the correct format for a multiple regression equation?

Select the correct answer below:

1. y=b0+b1x1+b2x2
2. y=b1x1+b2x2
3. y=b0+b1x1+b2x2+b3x3
4. y=b0+b1x1+b2x2+b3x3+b4x4