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): 35 49 51 54 65 51 52
47 87 37 46 33 39 44
39 64 94 34 30 48

Requried:
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%.
c. Calculate a point estimate of the population standard deviation.

(a) The point estimate of the population mean HDL cholesterol level is 49.95.

(b) The point estimate of the value that separates the largest 50% of HDL levels from the smallest 50% is 47.5.

(c) The point estimate of the population standard deviation is 16.85.

Step-by-step explanation:

We are given a sample of 20 observations on HDL cholesterol level (mg/dl) obtained from the survey below;

35, 49, 51, 54, 65, 51, 52,  47, 87, 37, 46, 33, 39, 44,  39, 64, 94, 34, 30, 48.

(a) The point estimate of the population mean HDL cholesterol level is given by the sample mean of the above data, i.e;

        Sample Mean,  =  

            =    

            =    =  49.95

So, the point estimate of the population mean HDL cholesterol level is 49.95.

(b) The point estimate of the value that separates the largest 50% of HDL levels from the smallest 50% is given by the Median of the above data.

Firstly, arranging the given data in ascending order we get;

30, 33, 34, 35, 37, 39, 39, 44, 46, 47, 48, 49, 51, 51, 52, 54, 64, 65, 87,  94.

Now, for calculating median we have to first observe that the number of observations (n) in our data is even or odd, i.e;

                      Median  =  

                      Median  =  

Here, the number of observations is even, i.e. n = 20.

So,   Median  =    

                      =  

                      =  

                      =  

        Median  =  47.5

Hence, the point estimate of the value that separates the largest 50% of HDL levels from the smallest 50% is 47.5.

(c) The point estimate of the population standard deviation is given by the following formula;

      Standard deviation, s  =  

       =  

       =  16.85

126 maybe. sorry