If a car is moving at 50 miles per hour on a level highway, then its braking distance depends on the road conditions. This distance in feet can be computed by D(x) = 250/30x where x is the coefficient of friction between the tires and the road and 0 < x ≤ 1. A smaller value of x indicates that the road is more slippery. 

(a) Identify and interpret the vertical asymptote. 

(b) Estimate the coefficient of friction associated with a braking distance of 340 feet.