Assume that the helium porosity (in percentage) of coal samples taken from any particular seam is normally distributed with true standard deviation 0.76. (a) Compute a 95% CI for the true average porosity of a certain seam if the average porosity for 19 specimens from the seam was 4.85. (Round your answers to two decimal places.) 5.19 4.51 (₁ (b) Compute a 98% CI for true average porosity of another seam based on 15 specimens with a sample average porosity of 4.56. (Round your answers to two decimal places.) ✓ , 5.02 4.10 (c) How large a sample size is necessary if the width of the 95% interval is to be 0.36? (Round your answer up to the nearest whole number.) 69 specimens (d) What sample size is necessary to estimate true average porosity to within 0.23 with 99% confidence? (Round your answer up to the nearest whole number.)

Calculus For The Life Sciences
2nd Edition
ISBN:9780321964038
Author:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Chapter2: Exponential, Logarithmic, And Trigonometric Functions
Section2.CR: Chapter 2 Review
Problem 111CR: Respiratory Rate Researchers have found that the 95 th percentile the value at which 95% of the data...
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Assume that the helium porosity (in percentage) of coal samples taken from any particular seam s normally distributed with true standard deviation 0.76.
(a) Compute a 95% CI for the true average porosity of a certain seam if the average porosity for 19 specimens from the seam was 4.85. (Round your answers to two decimal places.)
5.19
4.51
(b) Compute a 98% CI for true average porosity of another seam based on 15 specimens with a sample average porosity of 4.56. (Round your answers to two decimal places.)
4.10
, 5.02
(c) How large a sample size is necessary if the width of the 95% interval is to be 0.36? (Round your answer up to the nearest whole number.)
69
✔ specimens
(d) What sample size is necessary to estimate true average porosity to within 0.23 with 99% confidence? (Round your answer up to the nearest whole number.)
X specimens
Transcribed Image Text:Assume that the helium porosity (in percentage) of coal samples taken from any particular seam s normally distributed with true standard deviation 0.76. (a) Compute a 95% CI for the true average porosity of a certain seam if the average porosity for 19 specimens from the seam was 4.85. (Round your answers to two decimal places.) 5.19 4.51 (b) Compute a 98% CI for true average porosity of another seam based on 15 specimens with a sample average porosity of 4.56. (Round your answers to two decimal places.) 4.10 , 5.02 (c) How large a sample size is necessary if the width of the 95% interval is to be 0.36? (Round your answer up to the nearest whole number.) 69 ✔ specimens (d) What sample size is necessary to estimate true average porosity to within 0.23 with 99% confidence? (Round your answer up to the nearest whole number.) X specimens
A state legislator wishes to survey residents of her district to see what proportion of the electorate is aware of her position on using state funds to pay for abortions. (Round your answers up to the
nearest integer.)
USE SALT
(a) What sample size is necessary if the 95% CI for p is to have a width of at most 0.11 irrespective of p?
318
X people
(b) If the legislator has strong reason to believe that at least
156
people
of the electorate know of her position, how large a sample size would you recommend to maintain a width of at most 0.11?
You may need to use the appropriate table in the Appendix of Tables to answer this question.
Transcribed Image Text:A state legislator wishes to survey residents of her district to see what proportion of the electorate is aware of her position on using state funds to pay for abortions. (Round your answers up to the nearest integer.) USE SALT (a) What sample size is necessary if the 95% CI for p is to have a width of at most 0.11 irrespective of p? 318 X people (b) If the legislator has strong reason to believe that at least 156 people of the electorate know of her position, how large a sample size would you recommend to maintain a width of at most 0.11? You may need to use the appropriate table in the Appendix of Tables to answer this question.
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