The number of seconds that a yellow light should be on at a traffic interception is critical to safety at the signal.

One study found that, all other things being equal, the number of seconds that a yellow light should be on is a linear function of the width of the crossing-street in feet.

The formula they gave is: n(w)= 33 + 0.017w

a) Find the slope of the function and interpret what it means.

b) Find the vertical-intercept of the function and interpret what it means.