I. A study of the properties of metal plate-connected trusses used for roof yiel
ID: 3315248 • Letter: I
Question
I. A study of the properties of metal plate-connected trusses used for roof yielded the following observations on axial- stiffness index (kips in) for plate lengths 4, 6, 8. 10, and 12 in Observations (I) Lengths (1) 09.2 409.5 311.0 326.5 316.8 349.8 309. 402.1 347.2 3610 404.5 331.0 348.9 381.7 392.4 366.2 351.0 357. 409.9 367.3 382.0 346.7 452.9 4614 433.1 410.6 384.2 362.6 407.4 441.8 4199 410.7 473.4 441.2 465.8 12 A. (2 points) Complete the ANOVA table. (I Point) df Sum of Squares(SS) Mean Square(MS) Source of Variation Treatment Error 43,992.55 75.467.58 Total (I point) Based on the values that you found in part a, what is the hypotheses that should be considered in this experiment? B. (1 point) Does variation in plate length have any effect on true average axial stiffness with -0017 Explain. (1 Point) C.Explanation / Answer
A.
SSerror = SStotal - SStreatment = 75467.58 - 43992.55 = 31475.03
dftotal = n*k - 1 = 7*5 - 1 = 34
dftreatment = k - 1 = 5 - 1 = 4
dferror = dftotal - dftreatment = 34 - 4 = 30
MStreatment = SStreatment/dftreatment = 43992.55/4 = 10998.14
MSerror = SSerror/dferror = 31475.03/30 = 1049.17
F = MStreatment/MSerror = 10998.14/1049.17 = 10.48
B.
Null Hypothesis : H0 : There is no difference in axial stiffness index for different plate lengths.
Alternative Hypothesis : H1 : There is no difference in axial stiffness index for different plate lengths.
C.
The P-value corresponding to this F value is 0.00002.
Since the p-value is less than the significance level(0.01) , we will reject the null hypothesis. Hence evidence support that variation in plate length has effect on true average axial stiffness.