The following situation can be modeled by a linear function. Write an equation for the linear function and use it to answer the given question. Be sure you clearly identify the independent and dependent variables. Then briefly discuss whether a linear model is reasonable for the situation described.

A snowplow has a maximum speed of

30

miles per hour on a dry highway. Its maximum speed decreases by

1.8

miles per hour for every inch of snow on the highway. According to this model, at what snow depth will the plow be unable to move?

Select the correct choice below and fill in the answer box to complete your choice.

(Simplify your answer.)

A.The independent variable is the depth of snow (d), in inches, and the dependent variable is speed (s), in miles per hour. The linear function that models this situation is

s=

B.The independent variable is speed (s), in miles per hour, and the dependent variable is the depth of snow (d), in inches. The linear function that models this situation is

d=