31. Gateway Tours is choosing between two bus models. One is more expensive to pur- chase and maintain, but lasts much longer than the other. Its discount rate is 11%. It plans to continue with one of the two models for the foreseeable future; which should it choose? Based on the costs of each model shown below, which should it choose? Model 0 1 2 3 4 5... 7 Old Reliable -200 -4 -4 -4 -4 -4... -4 Short and Sweet -100 -2 -2 -2