need help in STAT

Assignment 10 Due: Wed. Dec 5, 2018 Stevens - Fall 2018

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CEE 4200 -- Assignment 10 Due: Wed. Dec 5, 2018

In Chapter 14: 14.3, 14.6, 14.12, 14.16

Stats 10.1

In the results from Stats 9.1, we found that the equation that relates the change in strength over ‘standard’ conditions (time = 48 hours and temperature = 25oC) was either

or depending on how you approached it (both are correct). The values for b from that analysis are in the table in the ‘Value’ column.

The standard errors for the parameter estimates were also reported in the Excel output, and from the Stats notes for the t-test a few weeks ago, we know that the standard error is actually the standard deviation divided by the square root of the sample size, so the standard deviation is found from and those values are found in the Std.Dev. columns of the table (n = 48 from Stats 9.1) (note, use these values regardless of what you got in Stats 9.1).

1. Use simulation to create and plot histograms of the 's for the two cases: a. ‘base case’ - that is t = 48 hours and T = 25oC b. ‘enhanced case’ - t = 72 hours (3 days) and T = 35oC

For this, assume that each of the parameters is described by a Normal distribution with the mean and standard deviation as in the table. 2. Determine the summary statistics for 's (mean, median, standard deviation, interquartile range) 3. If you require an improved concrete with the strength 0.05 ksi greater than the mean strength under

standard conditions, what is the risk that your concrete will NOT achieve the required strength?

b value

Model Model

Value Std. Dev Value Std. Dev b0 -0.48195 0.286 -0.0107 0.131 b1 0.000509 0.000552 0.000509 0.000552 b2 0.01787 0.0095 0.01787 0.0095

s' b0 b1t b2T+ += s' b0 b1 t 35–� � b2 T 25–� �+ +=

s' b0 b1t b2T+ += s' b0 b1 t 35–� � b2 T 25–� �+ +=

s SE n 2

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