Ali is deciding upon which courses to take by defining binary decision variables X1, X2, X3, X4, X5, ... for them and putting in an optimization model.

Taking at least one of X1 (statistics) or X2 (econometrics) is a pre-requisite of X3 (Operations Management 9500). In other words, Ali must take at least X1 or X2 in order to take X3.

X1 ______ X2 _________ 1 __________ X3

Choices for the first blank: a) + b) - c) * d) / Choices for the second blank: a) >= b) <= c) = d) < e) > Choices for the third blank: a) + b) - c) * d) /