Question

Person	Gender	Married	Age	Children	Salary	Spent
1	Male	Yes	35	1	78900	1610
2	Male	Yes	53	1	114100	1960
3	Male	Yes	36	2	84800	1470
4	Female	Yes	51	2	87500	1210
5	Male	Yes	39	2	85600	1320
6	Male	Yes	66	3	112800	310
7	Male	Yes	48	1	87300	1070
8	Male	Yes	36	1	73800	2080
9	Female	Yes	47	3	68500	900
10	Male	Yes	50	1	110200	1950
11	Male	No	59	0	103700	480
12	Male	Yes	64	1	136100	1210
13	Male	Yes	39	0	82600	2590
14	Male	Yes	56	3	131700	1240
15	Female	No	32	1	83000	4070
16	Male	Yes	49	1	123100	1590
17	Male	Yes	59	3	120900	1440
18	Male	Yes	50	2	88500	330
19	Female	Yes	35	2	50300	960
20	Male	Yes	44	3	90800	1380
21	Male	Yes	54	0	83100	590
22	Female	No	34	1	50600	940
23	Male	Yes	53	0	125600	1570
24	Male	Yes	45	1	104500	1440
25	Male	No	47	1	86900	1040
26	Male	Yes	52	3	105900	470
27	Male	Yes	40	0	103600	1660
28	Female	Yes	55	3	98300	920
29	Male	Yes	54	2	109700	1740
30	Male	No	46	0	88800	1130
31	Male	Yes	67	0	141700	1560
32	Female	No	43	1	69200	590
33	Male	Yes	52	2	132700	2800
34	Female	No	41	0	56600	1730
35	Male	Yes	60	3	81000	180
36	Male	Yes	52	1	122700	3120
37	Male	Yes	34	2	82100	990
38	Male	Yes	47	1	95200	930
39	Male	No	47	1	118100	2460
40	Female	No	47	0	84600	1680
41	Male	No	41	0	79700	1110
42	Male	Yes	58	3	114600	1070
43	Female	Yes	46	2	68300	490
44	Female	No	51	0	89500	1730
45	Female	Yes	52	2	73400	440
46	Male	Yes	59	2	87400	420
47	Male	No	41	0	90700	1820
48	Female	No	43	1	89000	2170
49	Female	Yes	63	3	79900	550
50	Male	No	43	0	111200	3000
51	Female	Yes	57	1	97600	870
52	Female	No	42	2	67200	1050
53	Female	No	52	2	103300	1400
54	Male	Yes	36	2	75200	1080
55	Male	Yes	46	3	102200	1950
56	Male	No	33	1	100400	3300
57	Male	Yes	64	0	147000	2350
58	Female	No	30	0	51600	780
59	Male	Yes	39	2	99900	1920
60	Male	No	31	0	77700	1620
61	Male	Yes	40	1	116300	1370
62	Male	No	29	1	90100	3430
63	Female	No	59	1	93000	710
64	Male	Yes	52	0	83600	480
65	Male	Yes	47	3	111500	1060
66	Female	Yes	45	1	96600	2750
67	Male	Yes	46	4	67900	200
68	Male	No	56	0	114500	1630
69	Male	Yes	57	4	130800	1770
70	Male	Yes	52	4	104800	1220
71	Female	No	39	1	60600	1150
72	Male	Yes	58	3	127000	2020
73	Male	Yes	38	1	87000	2540
74	Male	Yes	55	2	124700	1940
75	Female	No	38	3	51600	640
76	Male	Yes	57	2	129400	2120
77	Male	No	29	0	76700	2620
78	Male	Yes	52	2	126500	3080
79	Female	Yes	58	3	85200	470
80	Male	Yes	61	2	93800	180
81	Female	No	57	2	81900	550
82	Female	No	33	0	52100	950
83	Female	Yes	32	4	50900	810
84	Male	Yes	62	2	113700	320
85	Female	Yes	63	3	87400	680
86	Male	Yes	44	3	96800	2160
87	Male	Yes	55	1	146100	2740
88	Female	Yes	41	1	61900	880
89	Male	Yes	44	1	101000	2290
90	Female	Yes	53	1	92900	1320
91	Female	No	38	0	64800	1480
92	Male	Yes	60	0	149100	1780
93	Male	Yes	49	4	78600	680
94	Female	Yes	45	2	80700	2030
95	Male	Yes	49	2	111400	1960
96	Female	No	52	2	95300	1420
97	Male	Yes	53	1	144500	3270
98	Male	Yes	51	0	115500	2100
99	Male	Yes	42	2	89900	1970
100	Male	Yes	44	3	98400	650

The length of a 95% confidence interval for mean Age is which of the following? (Because of potential roundoff, choose the closest.)

a. 3.37

b. 4.27

c. 3.11

d. 3.72

Answer 1

sample std dev ,    s = √(Σ(X- x̅ )²/(n-1) ) =   9.3744
Sample Size ,   n =    100
Sample Mean,    x̅ = ΣX/n =    47.8000

Level of Significance ,    α =    0.05          
degree of freedom=   DF=n-1=   99          
't value='   tα/2=   1.9842   [Excel formula =t.inv(α/2,df) ]      
                  
Standard Error , SE = s/√n =   9.3744   / √   100   =   0.937437
margin of error , E=t*SE =   1.9842   *   0.93744   =   1.860

LENGTH of CONFIDENCE INTERVAL = 2*Margin of error =

= 2*1.86

=3.72

option (d)

................

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