MS 150 Statistic Quiz 7 Spring 2002 8.1

In the soy sauce survey the volumes of 37 bottles of soy sauce were recorded. The mean volume is 889 milliliters with a sample standard deviation of 590 milliliters. Construct a 95% confidence interval for the population mean volume for soy sauce based on this data.

1. ________ What is z-critical?
2. ________ What is the error E?
3. The confidence interval for the population mean µ is: _______ < µ < _______

Statistic or Parameter	Symbol	Equations	Excel
Normal Statistics
Calculate a z value from an x	z	=	=STANDARDIZE(x, µ, s)
Calculate an x value from a z	x	= s z + µ	=s*z+µ
Calculate a z-statistic from an x	z		=(x - µ)/(sx/SQRT(n))
Calculate a t-statistic (t-stat)	t		=(x - µ)/(sx/SQRT(n))
Calculate an x from a z			=µ + zc*sx/sqrt(n)
Find a probability p from a z value			=NORMSDIST(z)
Find a z value from a probability p			=NORMSINV(p)
Confidence interval statistics
Degrees of freedom	df	= n-1	=COUNT(data)-1
Find a zc value from a confidence level c	zc		=ABS(NORMSINV((1-c)/2))
Find a tc value from a confidence level c	tc		=TINV(1-c,df)
Calculate an error tolerance E of a mean for n >= 30 using sx	E		=zc*sx/SQRT(n)
Calculate an error tolerance E of a mean for n < 30 using sx. Can also be used for n >= 30.	E		=tc*sx/SQRT(n)
Calculate a confidence interval for a population mean µ from a sample mean x and an error tolerance E		x-E<= µ <=x+E