Adoctor wants to estimate the mean hdl cholesterol of all 20 to 29 year old females. how many subjects are needed to estimate the mean hdl cholesterol within 2 points with 99% confidence assuming s = 11.1 based on earlier studies? suppose the doctor would be content with 95% confidence. how does the decrease in confidence affect the sample size?

99% requires subjects

95% requires subjects

how does the decrease in confidence affect the sample size?

99% confidence requires 243 subjects

95% confidence requires 118 subjects

The decrease in confidence makes the sample size smaller.

Step-by-step explanation:

The sample size n in Simple Random Sampling is given by

where  

z = 2.807 is the critical value for a 99% confidence level (*)

s = 11.1 is the estimated population standard deviation

e = 2 points is the margin of error

so  

(*)This is a point z such that the area under the Normal curve N(0,1) outside the interval [-z, z] equals 1% = 0.001

It can be obtained in Excel with

=NORMINV(1-0.0025,0,1)

and in OpenOffice Calc with

=NORMINV(1-0.0025;0;1)

A 95% confidence level would only change the value of z, which now would be 1.96, and the sample size changes to

The decrease in confidence makes the sample size smaller.

answer: the answer is ann

answer: first option i.e. 'a' is correct.

step-by-step explanation:

since we have given that

number of minutes to wrap a small gift box = 4 minutes

we need to find the number of gifts to be wrapped in 5 minutes

since there is a direct variation, as the number of minutes will increase with   number of gifts to be wrapped.

so, let the number of gifts to be wrapped in 5 minutes be x.

so, it becomes,

hence, first option 'a'   is correct.