Call
At L=4, K=4 MPl = 2, MPk = 3. Marginal Rate of Technical Substitution (MRTS) is the amount by which the quantity of one input has to be reduced when one extra unit of another input is used, so that output remains constant. MRTS(K, L) = MPk/MPl = 2/3 = 0.67 So, the marginal rate of technical substitution is 0.67.