A school is organizing a cookout where hotdogs will be served. The hotdogs come in small packs and large packs. Each small pack has 10 hotdogs and each large pack has 18 hotdogs. The school bought 6 packs of hotdogs that have a total of 76 hotdogs. Write a system of equations that could be used to determine the number of small packs purchased and the number of large packs purchased. Define the variables that you use to write the system. .

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.