Write up the fourth regression

Question

Problem:

See the following data file.

WEEKLY SALES PERIOD	DEMAND         IN CASES,        Q	PRICE         PER CASE,  P	COMPETITOR PRICE,             Px	ADVERT.,     Ad	INCOME,  Y	MONTH, T	FORECAST DEMAND,   Q
1	1290	$137	$94	$814	$42,498	1	$1,287
2	1177	147	81	896	41399	2	1187
3	1155	149	89	852	39905	3	1188
4	1299	117	92	854	34871	4	1311
5	1166	135	86	810	34239	5	1175
6	1186	143	79	768	44452	6	1200
7	1293	113	91	978	30367	7	1317
8	1322	111	82	821	37757	8	1321
9	1338	109	81	843	40130	9	1359
10	1160	129	82	849	31264	10	1172
11	1293	124	91	797	34610	11	1262
12	1413	117	76	988	41033	12	1349
13	1299	106	90	914	30674	13	1341
14	1238	135	88	913	31578	14	1196
15	1467	117	99	867	41201	15	1430
16	1089	147	76	785	30247	16	1032
17	1203	124	83	817	33177	17	1222
18	1474	103	98	846	37330	18	1453
19	1235	140	78	768	44671	19	1230
20	1367	115	83	856	37950	20	1333
21	1310	119	76	771	43478	21	1316
22	1331	138	100	947	36053	22	1306
23	1293	122	90	831	35333	23	1300
24	1437	105	86	905	44304	24	1484
25	1165	145	96	996	30925	25	1214
26	1328	138	97	929	36867	26	1300
27	1515	116	97	1000	41799	27	1485
28	1223	148	84	951	40684	28	1238
29	1293	134	88	848	43637	29	1331
30	1215	127	87	891	30468	30	1235

Run a regression of sales = f(price),
sales = f(price, competitor price),
sales = (price, competitor price, advertising),
sales = f(price , Competitor price, advertising, income)
and set up the hypothesis test/t-test,
then write up the 4th regression