RES 341 chapter exercise 8.46

# RES 341 chapter exercise 8.46 - grams with 90 percent...

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8.46 A random sample of 10 miniature Tootsie Rolls as taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were 3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477 df = n – 1 = 10 – 1 = 9 (a) Construct a 90 percent confidence interval for the true mean weight. n=10 x-bar= 3.3047 The standard error is E = 1.645(s/sqrt(10)) = 1.645[0.131989/sqrt(10)]=1.645*0.41739 =0.06866 90% C.I. = (x-bar-E,x-bar+E) = (3.3048-0.06866, 3.3048+0.06866) Sample mean (x-bar) is 3.304800 E= 0.06866 (b) What sample size would be necessary to estimate the true weight with an error of ± 0.03
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Unformatted text preview: grams with 90 percent confidence? n = [z*sigma/E]^2 E = z*sigma/sqrt(n) z* for 90% confidence = 1.645 sigma = 0.13199 E = 0.03 n=[z'*s/E]^2 n=[1.645*0.131989/0.03]^2 = 7.237397^2 = 52.3799; n=53 (c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture. (Data are from a project by MBA student Henry Scussel.) There are many random variables during the production. Temperature, consistency of batches, machine tolerances, and machine operators might cause variation in the weight of the Tootsie Roll....
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## This note was uploaded on 06/25/2011 for the course RES 341 taught by Professor Hermis during the Spring '10 term at University of Phoenix.

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