Engineering Pathfinder - Engineering Statistics III Questions And Answers Rated A+ New Update Assured Satisfaction

Which is the Two-Sided Confidence Interval? - Answer-(L < μ < U) with __ % Confidence Which is the Sample Size? - Answer-n The fuel efficiency of a new car is tested, resulting in a 2-side confidence interval of (45.6 mpg ≤ μ ≤ 51.1 mpg) with 95 % Confidence. Which conclusion is correct? - Answer-The car's fuel efficiency is not significantly different than 50 mpg, at a confidence level of 95% A new battery is expected to have a storage capacity of 60 ampere-hour (A h). A sample is tested, resulting in a 2-side confidence interval of (55 A h ≤ μ ≤ 65 A h) with 97.5 % Confidence. Which conclusion is correct? - Answer-The battery storage capacity is not significantly different than 60 A h, at a confidence level of 97.5 % Two deposits of coal are expected to have different energy content (per ton). Samples of the two type are tested to determine their means, standard deviations, and standard errors of the mean. The two means are compared using error bars that are twice the standard error of the mean. What does it mean if the bars overlap? - Answer-The mean energy contents ARE NOT different in a statistically significant way Two water pipes are expected to burst at different pressures. Samples of the two type are tested to determine their means, standard deviations, and standard errors of the mean. The two means are compared using error bars that are the 95 % confidence interval. What does it mean if the bars overlap? - Answer-No statistical inference can be made (AFTER QUESTIONS - 2 sided CI - mean (first one), parts 1-3) X (mean) = 201.3 s (standard dev) = 19.7 n (sample size) = 22 confidence = 99.5%1. If you repeated this problem many times--with a new sample collected from X each time--what percentage of the Confidence Intervals thus estimated would you expect to include the true mean? 2. What is the Significance of the Confidence Interval? Note: answer is decimal, NOT percent. - Answer-1. 99.5% (you would expect the true mean to be in the same percentage of confidence interval) 2. a = 1 - 0.995 = 0.00500 (subtract confidence interval from 1) 3. a = 0.005/2 = 0.0025 (each tail has half the significance of the confidence interval) (AFTER QUESTIONS - 2 sided CI - mean (first one), parts 4-7) X (mean) = 201.3 s (standard dev) = 19.7 n (sample size) = 22 confidence = 99.5% 4. Calculate the Degrees of Freedom. 5. Calculate the Critical Value used to determine the Confidence Limit(s). Use a Student T Table. 6 & 7. Calculate the Lower and Upper Limit of the Confidence Interval. - Answer-4. 21 (v = n - 1) 5. 3.135 ( In calculator 2nd vars, select #4, invT(0.0025,21) invT(#3 answer, #4 answer) invT(half the significance of the confidence interval, degrees of freedom) 6 & 7. 201.3 +/- (3.135 * 19.7 / (22^1/2)) X - T(s/(n^1/2)) (AFTER QUESTIONS - HT 2)1. Enter: (1) if the 2 sided confidence interval indicates that the capacity IS significantly different from the hypothesized capacity; (2) if the 2 sided confidence interval indicates that the capacity is NOT significantly different from the hypothesized value. U = 7.17 L = 5.37 Its hypothesized capacity (in liters) is: C = 5.82 - Answer-The bladder capacity is NOT significantly different from its hypothesized capacity