Question

a. a 95% confidence interval for the population mean Age;
b. a 99% confidence interval for the population mean Income;
c. a 90% confidence interval for the population proportion of Males.

use ms excel file

Product	Age	Gender	Education	Marital Status	Usage	Fitness	Income	Miles
TM195	18	Male	14	Single	3	4	29562	112
TM195	23	Male	16	Partnered	4	3	39795	94
TM195	24	Female	16	Single	4	3	46617	75
TM195	26	Male	16	Partnered	2	2	53439	47
TM195	29	Female	14	Partnered	2	2	46617	38
TM195	34	Male	16	Single	4	5	51165	169
TM195	38	Male	16	Partnered	3	3	56850	75
TM498	20	Female	14	Partnered	3	3	34110	106
TM498	20	Male	14	Single	3	3	38658	95
TM498	23	Male	16	Partnered	4	3	45480	127
TM498	25	Female	14	Partnered	2	3	45480	85
TM498	25	Male	14	Partnered	4	3	45480	170
TM498	25	Male	14	Partnered	3	4	43206	106
TM498	25	Male	16	Partnered	2	3	50028	53
TM498	31	Female	16	Partnered	2	3	51165	64
TM498	34	Male	16	Partnered	3	4	59124	85
TM498	34	Male	15	Single	3	3	67083	85
TM498	40	Female	16	Partnered	3	3	61398	85
TM798	22	Male	16	Single	3	5	54781	120
TM798	23	Male	16	Single	4	5	58516	140
TM798	25	Female	18	Partnered	5	5	61006	200
TM798	25	Male	18	Partnered	6	4	70966	180
TM798	34	Male	16	Single	5	5	92131	150
TM798	48	Male	18	Partnered	4	5	95508	180

Answer 1

Males: Sample size-n- 24 Using Excel Sample proportion of males 0.7083 Standard Error of the point estimate = σ 17 24 p(1-p) 0.7083 (1-0.7083) = 0.0928 24 For 90% confidence interval, α-1-0.90-0.10 a/2-0.10/2-0.05 From t-distribution table, the value of t having an area of (a/2 0.05) in its upper tail and for (df 23) is given by Z0.05 = 1.645 Margin of Error: MoE 1.645 × 0.0928 MoE = 0.1526 90% confidence interval: Lower Limit of 90% confidence interval for the population proportion of Males = 0.7083-0.1526 = 0.5557 Upper Limit of 90% confidence interval for the population proportion of Males-0.7083 0.1526 0.8609