Coordinate plane with two lines graphed. The equations of the lines are y equals negative two-thirds x plus four and the other line is y equals two-thirds x. Determine the number of solutions the system of linear equations has and the solution(s) to the equations represented by these two lines? The system of equations has 0 solutions, because the graph has no point of intersection. The system of equations has infinite number of solutions and all real numbers satisfy both equations. The system of equations has 1 solution and it is (3, 2). The system of equations has 1 solution and it is (3, 0).

Aprisoner is trapped in a cell containing three doors. the first door leads to a tunnel that returns him to his cell after two days of travel. the second leads to a tunnel that returns him to his cell after three days of travel. the third door leads immediately to freedom. (a) assuming that the prisoner will always select doors 1, 2 and 3 with probabili- ties 0.5,0.3,0.2 (respectively), what is the expected number of days until he reaches freedom? (b) assuming that the prisoner is always equally likely to choose among those doors that he has not used, what is the expected number of days until he reaches freedom? (in this version, if the prisoner initially tries door 1, for example, then when he returns to the cell, he will now select only from doors 2 and 3.) (c) for parts (a) and (b), find the variance of the number of days until the prisoner reaches freedom. hint for part (b): define ni to be the number of additional days the prisoner spends after initially choosing door i and returning to his cell.