zewdu tasew & 4/27/17 5:26 PM statisticsON2017 Save Homework: practice problems
ID: 3229285 • Letter: Z
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zewdu tasew & 4/27/17 5:26 PM statisticsON2017 Save Homework: practice problems module 13 Score: 0 of 1 pt 1 of 3 (0 complete) HW Score: 0%, 0 of 3 pts Question Help 7.4.11 A simple random sample from a population with a normal distribution of 105 body temperatures hasx 98,40°F and s 0.68 F.Construct a 90% confidence interval estimate of the standard deviation of body temperature of all healthy humans. ls it safe to conclude that the population standard deviation is less than 1.70 F? Click the icon to view the table of Chi-square critical values. (Round to two decimal places as needed.)Explanation / Answer
7.4.11 Chi-square value for 95% confidence interval and degree of freedom (105-1 = 104) are (81.47, 128.80)
Upper bound = sqrt((N-1)s^2/Chi-sq) = sqrt((105-1)0.68^2/81.47) = 0.77
Lower bound = sqrt((N-1)s^2/Chi-sq) = sqrt((105-1)0.68^2/128.80) = 0.61
So, the answer is (0.60, 0.79)
Yes, it is safe to conclude that the population standard deviation is less than 1.7 degree F as we are 90 % confident that the standard deviation lies between 0.60 and 0.79.
7.4.5-T The degree of freedom = n-1 = 30-1 = 29
7.4.9 Chi-square value for 80% confidence interval and degree of freedom (91-1 = 90) are (73.29, 107.57)
Upper bound = sqrt((N-1)s^2/Chi-sq) = sqrt((91-1)16496^2/73.29) = 18280.06
Lower bound = sqrt((N-1)s^2/Chi-sq) = sqrt((91-1)16496^2/107.57) = 15088.79
So, the answer is (15088.79, 18280.06)
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