Asurvey is planned to determine the mean annual family medical expenses of employees of a large company. the management of the company wishes to be 90% confident that the sample mean is correct to within plus or minus$40 of the population mean annual family medical expenses. a previous study indicates that the standard deviation is approximately $341. a. how large a sample is necessary?

b. if management wants to be correct to within (plus or minus $25), how many employees need to be selected?

Part A:

n=196.66≅197 employees

Part B:

n=503.45≅503 employees

Step-by-step explanation:

Part A:

The formula we are going to use to find a sample size is gien below::

Where:

n is the sample size

Z is the distribution

S is the standard deviation

E is the margin

S=341, E=40

Z is calculated as:

Alpha=1-0.90

Alpha=0.1

Alpha/2=0.1/2

Alpha/2=0.05

From Standard distribution table Z at Alpha/2 is 1.645

n=196.66≅197 employees

Part B:

S=341, E=25, Z=1.645

n=503.45≅503 employees

step-by-step explanation:

. your answer will contain x - and y -terms. (1 point) x ( ¿¿ 2 − 7 ) 2 +( y 2 − 9 ) 2 √ ¿ 12. what is the distance from the directrix (the crocodile river) to the point ( x , y )? write this equation. your answer will contain a y -term.

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step-by-step explanation: