Question 135349
A random sample of 10 miniature Tootsie Rolls was 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
(a) Construct a 90 percent confidence interval for the true mean weight.
x-bar = 3.3048
E = 1.645*[0.131989/sqrt(10)] = 0.06866
CI: (3.3048-0.06866,3.3048+0.06866)
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(b) What sample size would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence?
n = [z*sigma/E]^2
n = [1.645*0.131989/0.03]^2 = 52.38
Rounding up get n = 53
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(c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture.
machine tolerances, temperature, handling
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Cheers,
Stan H.