In a learning model proposed by C. L. Hull, the habit strength H of an individual is related to the number r of reinforcements by the equation

H(r) = M(1 − e^−kr)

a. Sketch the graph of H(r). What happens to H(r) as r→ + ∞?

b. Show that if the number of reinforcements is doubled from r to 2r, the habit strength is multiplied by 1 + e^−kr.