Question

A survey collects demographic, socioeconomic, dietary, and health-related information on an annual basis. Here is a sample of 20 observations on HDL cholesterol level (mg/dl) obtained from the survey (HDL is "good" cholesterol; the higher its value, the lower the risk for heart disease). 34 49 53 55 64 50 50 47 87 37 46 32 40 45 38 64 94 36 31 48 (a) Calculate a point estimate of the population mean HDL cholesterol level. (b) Making no assumptions about the shape of the population distribution, calculate a point estimate of the value that separates the largest 50% of HDL levels from the smallest 50% 47.5 (c) Calculate a point estimate of the population standard deviation. (Round your answer to three decimal places.) 16.717 (b) An HDL level of at least 60 is considered desirable as it corresponds to a significantly lower risk of heart disease. Making no assumptions about the shape of the population distribution, estimate the proportion p of the population having an HDL level of at least 60. P-02 Need Help? Read It Watch Talk to a Tutor

Answer 1

Ans:

	xi	(xi-50)^2
1	34	256
2	49	1
3	53	9
4	55	25
5	64	196
6	50	0
7	50	0
8	47	9
9	87	1369
10	37	169
11	46	16
12	32	324
13	40	100
14	45	25
15	38	144
16	64	196
17	94	1936
18	36	196
19	31	361
20	48	4
Total	1000	5336
mean	50

mean=1000/20=50

median=(47+48)/2=47.5

c)

Point estimate of population standard deviation=sqrt(5336/(20-1))=16.758