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July 31, 2014

July 31, 2014

Posted by **Lexi** on Monday, October 20, 2008 at 2:01pm.

A certain air plane has 2 independent alternators to provide electrical power. The probability that one will fail is .02, what is the probability that.

(a) Probability both will fail = 0.0004

(b) Probability neither will fail (both will work fine) = 0.9604

(c) Probability one will fail = 0.0392

Problem 2:

A random sample of 10 miniature tootsie rolls was taken from a bag, each piece weighed on a very accurate scale. The results in grams were: 3.087 3.131 3.241 3.241 3.27 3.353 3.4 3.411 3.437 3.477

a)construct a 90% confidence interval for the true mean weight.

b)what sample size would be necessary to estimate the true weight with an error of .03 grams with 90% confidence.

c)discuss the factors which might cause variations in the weight of tootsie rolls during manufacturing.

Answers to a, b, and c:

A.

Sample mean 3.3048

Sample SD (s) 0.1320

Sample size (n) 10

Since sample size is smaller than 30, we will use a t-distribution.

Degree of freedom 9

Confidence level 90%

Critical tc 1.833

Margin of error 0.0765

Lower limit 3.2283

Upper limit 3.3813

B.

Margin of error 0.03

Confidence level 90%

Critical tc 1.833

SD 0.1320

Required sample size 65.04451373

Rounded up 6o 66.

C.

Factors include:machines that divide the raw material cannot divide perfectly equally. Although each was weighed on a very accurate scale there is still error of measurement. The temperature utilized during candy manufacture, sharpness of cutting tools utilized to form pieces.

- Statistics -
**Lexi**, Monday, October 20, 2008 at 2:32pmProblem 2:

A random sample of 10 miniature tootsie rolls was taken from a bag, each piece weighed on a very accurate scale. The results in grams were: 3.087 3.131 3.241 3.241 3.27 3.353 3.4 3.411 3.437 3.477

a)construct a 90% confidence interval for the true mean weight.

b)what sample size would be necessary to estimate the true weight with an error of .03 grams with 90% confidence.

c)discuss the factors which might cause variations in the weight of tootsie rolls during manufacturing.

Answers to a, b, and c:

A.

Sample mean 3.3048

Sample SD (s) 0.1320

Sample size (n) 10

Since sample size is smaller than 30, we will use a t-distribution.

Degree of freedom 9

Confidence level 90%

Critical tc 1.833

Margin of error 0.0765

Lower limit 3.2283

Upper limit 3.3813

B.

Margin of error 0.03

Confidence level 90%

Critical tc 1.833

SD 0.1320

Required sample size 65.04451373

Rounded up 6o 66.

C.

Factors include:machines that divide the raw material cannot divide perfectly equally. Although each was weighed on a very accurate scale there is still error of measurement. The temperature utilized during candy manufacture, sharpness of cutting tools utilized to form pieces.

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