Problem 3 (30%) Problem 11-1 in Roess, Prassas, McShane, 5th ed. (edited - omit part f) Consider the spot speed data below, collected at a rural highway site under conditions of uncongested flow: Speed Group (mi/h) Number of Vehicles Observed (N) 15-20 0 20-25 4 25-30 9 30-35 18 35-40 35 40-45 42 45-50 32 50-55 20 55-60 9 60-65 0 a. Plot the frequency and cumulative frequency curves for this data. b. Determine the median speed, the modal speed, the pace, and the percentage of vehicles in the pace from the curves and show how each was found. c. Compute the mean and standard deviation of the speed distribution. d. What are the confidence bounds of the estimate of the true mean speed of the distribution with 95% confidence? With 99.7% confidence? e. Based on the results of this study, a second study is to be conducted to achieve a tolerance of ±0.8 mi/h with 95% confidence. What sample size is required?
Problem 3 (30%) Problem 11-1 in Roess, Prassas, McShane, 5th ed. (edited - omit part f) Consider the spot speed data below, collected at a rural highway site under conditions of uncongested flow: Speed Group (mi/h) Number of Vehicles Observed (N) 15-20 0 20-25 4 25-30 9 30-35 18 35-40 35 40-45 42 45-50 32 50-55 20 55-60 9 60-65 0 a. Plot the frequency and cumulative frequency curves for this data. b. Determine the median speed, the modal speed, the pace, and the percentage of vehicles in the pace from the curves and show how each was found. c. Compute the mean and standard deviation of the speed distribution. d. What are the confidence bounds of the estimate of the true mean speed of the distribution with 95% confidence? With 99.7% confidence? e. Based on the results of this study, a second study is to be conducted to achieve a tolerance of ±0.8 mi/h with 95% confidence. What sample size is required?
Chapter2: Loads On Structures
Section: Chapter Questions
Problem 1P
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Transcribed Image Text:Problem 3 (30%)
Problem 11-1 in Roess, Prassas, McShane, 5th ed. (edited - omit part f)
Consider the spot speed data below, collected at a rural highway site under conditions of
uncongested flow:
Speed Group (mi/h) Number of Vehicles Observed (N)
15-20
0
20-25
4
25-30
9
30-35
18
35-40
35
40-45
42
45-50
32
50-55
20
55-60
9
60-65
0
a. Plot the frequency and cumulative frequency curves for this data.
b. Determine the median speed, the modal speed, the pace, and the percentage of vehicles in the
pace from the curves and show how each was found.
c. Compute the mean and standard deviation of the speed distribution.
d. What are the confidence bounds of the estimate of the true mean speed of the distribution
with 95% confidence? With 99.7% confidence?
e. Based on the results of this study, a second study is to be conducted to achieve a tolerance of
±0.8 mi/h with 95% confidence. What sample size is required?
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