Ajuice shop owner wants to know the average amount of juice his staff puts into each glass. a sample of 50 glasses was found to have an average (mean) of 245 ml. if the known standard deviation of the amount of juice in each glass is 4 ml for the entire population, what is the margin of error of the sample mean?

a)1.13 ml
b)1.24 ml
c)1.35 ml
d)1.49 ml

So its A) 1.13 they should ask you for a margin of error that is within some sort of range if we wanted a margin of error of 2% etc .02 = z(.5657) z = 2/(56.57) or about .04 but thats usually not what is asked. they usually want to know what size sample we should get to be say 95% confident that the margin of error is with 2% .02 = 1.96(4/sqrt(n)) and we can solve for n

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