A Research Project Studied the Physical Properties of Wood Materials

Multiple Choice

A research project studied the physical properties of wood materials constructed by bonding together small flakes of wood.The two factors considered were the size of the flakes and species of tree.The sizes of the flakes were S1: 0.15 inches by 2 inches and S2: 0.25 inches by 2 inches,and the species of tree used were aspen,birch,and maple.For each combination of flake size and tree species,three samples of wood material were constructed.For each sample,the physical property measured was the tension modulus of elasticity in the direction perpendicular to the alignment of the flakes,in pounds per square inch (psi) .The table below gives the means for the different size-species groups. What are the marginal means for species?

A) 387.33,292.67,and 323.33
B) 335.67,455.33,and 293.67
C) 723,748,and 617
D) 361.50,374.00,and 308.50