The number of people riding the subway daily from Silver Spring, Maryland, to Washington’s Metro Center is a function f(x) of the fare, x cents. If f(235) = 4600 and f′(235) = -100, approximate the daily number of riders for each of the following costs:

(a) 237 cents 

(b) 234 cents

(c) 240 cents 

(d) 232 cents