SOLUTION: I dont uunderstand how to utilize 90% confidence and how it works in the problem, thank you! A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was w

Question 251867: I dont uunderstand how to utilize 90% confidence and how it works in the problem, thank you!
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. (b) What sample size
would be necessary to estimate the true weight with an error of +/- 0.03 grams with 90 percent confidence?
(c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture.

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
I dont understand how to utilize 90% confidence and how it works in the problem, thank you!
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.
sample mean = 3.3048 grams ; sample std = 0.1320
---
standard error = 1.645*0.1320 = 0.2171
--
90% CI: 3.3048 - 0.2171 < u < 3.3048 + 0.2171
90% CI: 3.0877 < u < 3.5219
-------------------------------------
(b) What sample size would be necessary to estimate the true weight with an error of +/- 0.03 grams with 90 percent confidence?
---
n = [1.645*0.2171/0.03]^2
n = 11.90^2
n = 141.7
Rounding up n = 142
-------------------------------------

(c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture.
Discuss machinery. termperature, ingrediant, and human variables.
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Cheers,
Stan H.

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