The file contains the daily closing prices of American Express stock for a one-year period.
a. Using a span of 3, forecast the price of this stock
for the next trading day with the moving average method. How well does this method with span 3 forecast the known observations in this series?
b. Repeat part a with a span of 10.
c. Which of these two spans appears to be more appropriate? Justify your choice.

Day	Closing Price
1	88.56
2	88.98
3	88.49
4	88.45
5	87.78
6	86.77
7	87.27
8	87.28
9	86.51
10	86.25
11	87.22
12	87.92
13	88.94
14	88.54
15	87.84
16	87.17
17	87.38
18	85.64
19	87.23
20	86.82
21	86.41
22	84.96
23	85.01
24	86.29
25	86.16
26	84.50
27	86.54
28	85.03
29	84.14
30	81.96
31	81.92
32	80.12
33	79.44
34	81.76
35	83.17
36	84.79
37	83.12
38	84.76
39	85.54
40	85.77
41	87.13
42	87.46
43	87.86
44	89.05
45	89.95
46	90.47
47	91.50
48	90.67
49	91.34
50	91.48
51	90.83
52	90.64
53	90.16
54	89.77
55	89.23
56	89.68
57	89.60
58	89.72
59	89.49
60	90.13
61	90.49
62	90.54
63	91.50
64	91.22
65	92.07
66	90.34
67	90.92
68	91.73
69	92.63
70	92.43
71	91.83
72	92.20
73	90.09
74	89.14
75	87.36
76	89.54
77	92.24
78	91.97
79	92.69
80	92.89
81	93.14
82	93.35
83	93.33
84	93.33
85	92.11
86	92.09
87	89.66
88	87.75
89	89.66
90	90.93
91	89.78
92	88.87
93	88.60
94	86.46
95	85.27
96	85.43
97	86.65
98	87.05
99	83.78
100	83.54
101	82.71
102	81.82
103	81.15
104	81.42
105	80.12
106	81.55
107	83.14
108	83.02
109	84.13
110	84.41
111	84.38
112	85.24
113	85.40
114	79.91
115	77.53
116	78.52
117	79.22
118	77.85
119	79.27
120	79.73
121	80.29
122	81.59
123	82.66
124	81.02
125	81.45
126	81.33
127	80.06
128	80.58
129	79.74
130	79.94
131	78.55
132	78.89
133	80.99
134	80.03
135	80.93
136	80.49
137	81.28
138	80.97
139	82.12
140	81.62
141	80.80
142	79.55
143	77.93
144	77.42
145	77.50
146	77.83
147	78.64
148	79.40
149	79.33
150	78.04
151	78.40
152	78.86
153	79.29
154	78.97
155	79.19
156	79.45
157	80.61
158	77.03
159	76.94
160	76.99
161	78.15
162	77.86
163	77.70
164	77.20
165	77.20
166	76.87
167	77.16
168	77.39
169	77.99
170	77.55
171	77.56
172	78.14
173	78.69
174	79.40
175	78.79
176	79.56
177	80.45
178	79.92
179	79.87
180	81.06
181	80.66
182	80.46
183	80.95
184	79.89
185	79.81
186	79.79
187	79.42
188	79.17
189	79.69
190	80.30
191	79.06
192	79.09
193	78.52
194	78.87
195	79.89
196	80.00
197	79.23
198	78.95
199	79.06
200	80.02
201	80.47
202	79.89
203	80.95
204	81.06
205	80.44
206	79.58
207	79.58
208	77.51
209	77.72
210	78.40
211	78.21
212	77.59
213	77.55
214	75.93
215	76.34
216	77.31
217	78.53
218	78.97
219	78.54
220	78.92
221	79.22
222	79.30
223	78.95
224	78.99
225	77.01
226	75.90
227	74.92
228	75.11
229	75.70
230	76.12
231	76.06
232	75.98
233	75.72
234	75.59
235	75.00
236	79.72
237	81.26
238	81.34
239	81.00
240	80.76
241	80.91
242	81.00
243	81.24
244	80.95
245	78.76
246	77.03
247	74.65
248	73.52
249	75.63
250	76.88
251	76.65
252	76.72
253	74.00