topic: Non-linear Programming Problem a Location Problem with Two Sites.

By using Excel Solve, solve this problem: Oliveira Office Supply has a large retail system consisting of twelve stores spread around the country, often in direct competition with Kilroy. However, managers at Oliveira have decided to use two national distribution centers. When Oliveira's stores are mapped on the same grid as Kilroy's, the store locations occur at the coordinates listed in the following table.

Coordinates			Trips
Site (k)	xk	yk	nk
1	2	96	21
2	5	41	12
3	20	10	20
4	44	48	15
5	60	58	27
6	100	4	8
7	122	94	21
8	138	80	16
9	150	40	10
10	170	18	18
11	182	2	25
12	190	56	14

A. Find the optimal location for Oliveira's two distribution centers in this expanded version of the problem.

B. What is the optimal value of the objective function?