Palisades Eco-Park is a small ecological reserve that admits a relatively small number of visitors on any day, but provides both educational and entertaining lectures, exhibitions, and opportunities to observe nature. The company has collected the following data on labor costs and number of visitors to the park over the last 30 months.

Month	Labor Cost		Visitors
1	$	26,720	2,600
2	$	37,555	3,964
3	$	41,361	4,299
4	$	32,751	3,398
5	$	36,022	3,630
6	$	33,811	3,336
7	$	33,139	3,372
8	$	39,671	4,093
9	$	39,912	4,222
10	$	48,568	5,463
11	$	43,627	4,551
12	$	40,390	4,289
13	$	35,644	3,694
14	$	34,330	3,573
15	$	38,260	3,836
16	$	27,424	3,210
17	$	31,732	5,195
18	$	31,005	4,260
19	$	28,552	3,689
20	$	31,049	4,546
21	$	26,588	3,058
22	$	25,515	2,744
23	$	29,899	4,997
24	$	31,204	5,838
25	$	29,099	3,964
26	$	32,795	5,007
27	$	29,650	4,572
28	$	30,970	4,665
29	$	29,429	3,841
30	$	28,846	3,174

Required:

a. Estimate the labor costs assuming 3,400 visitors for the month using the results of a simple regression based on the 30 months of available data. b. What percentage of the variance in the data does the R-squared value explain? c. You learn that starting in month 16, the park started using a different, more automated system for interacting with visitors. Estimate the labor cost assuming 3,400 visitors using the results of a simple regression based on the data for months 16 through 30 only. d. What percentage of the variance in the data does the R-squared value explain?