Consider the following diagram of one-way roads, with indicated traffic flow on some roads. Compute the values of X1, X2, X3, X4, X5, X6. 100 cars/h A X1 B X2 X3 E C 80 cars/h 50 cars/h --- X4 → 120 cars/h 40 cars/h X6 *5 D 140 cars/h Compute the values of X1, X2, X3, X4, X5, X6. x1= x2 = How to enter the solution: 个 E 40 cars/h C 80 cars/h 50 cars/h X6 ts D -- 140 cars/h If the value of a variable is a number, just enter the number. . If the value of a variable is a formula involving free variables, enter the formula. For example, if you obtain that x1 = 1-2x2 + 3x3 where x2 and x3 are free, then as to indicate subscripts of variables, and the value of x1 you should enter 1 - 2*x_2 + 3*x_3 . Use the underscore . If a variable is a free variable, enter the variable name as its value. For example, if x2 is a free variable, then you should enter ✗_2 to indicate multiplication. as the value of x2. x4= x5 = x3= x6 =

In a traditional class with in-class tests, a question that is often asked after a class exam is, "What was the class average?" If that question is asked and the professor says that the class average was 80, what information do the students gain by knowing that? I want you to focus on both what the individual students knows about their own grade as well as what the students know about the class's grades on that exam.

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could this be done by a human?