Problem 2: A three-zone system with 900 home-based shopping productions is shown in the following Table. Zones 1 and 2 each generate 400 productions, while zone 3 generates 100 productions. Each zone contains a shopping mall with 300 attractions. The shopping mall in zone 1 can be easily reached due to the parking availability and transit service. Thus, F11, F21, and F31 1.0. Parking costs at the shopping mall in zone 2 are moderate with some transit service. Thus, F12, F22, and F32 0.5. Parking costs at the mall in zone 3 is high and transit service is unavailable. Thus, F13, F23, and F33 0.2. F represents the friction factors Provide trip distribution calculation using the gravity model for (a) singly-constrained and (b) doubly-constrained gravity model. Table: Home-Based Shopping Productions and Attractions Zone Productions Attractions 400 400 100 900 300 300 300 900 Total