1. The strength of five types A, B, C, D and E of fibre-board were being compared. Four boards of each type were tested. The modulus of rupture of each of the 20 boards is given in the following...

1.    The strength of five types A, B, C, D and E of fibre-board were being compared. Four boards of each type were tested. The modulus of rupture of each of the 20 boards is given in the following table:


A    B    C    D    E
619    424    392    462    465
674    525    494    559    568
633    549    441    556    613
622    601    457    611    611




a)    Use Bartletts test to determine if the within board variances are significantly different (α = 0.05).
b)    Perform analysis of variance and draw your conclusions (α = 0.05).
c)    Use Bonferronis Multiple Comparison Test, with a 0.05 level of significance, to compare the means. Discuss your results.
d)    Calculate 95% confidence limits for the difference of means D and E


2.    The following are the yields in kilograms of above-ground biomass per plot that resulted when four levels of nitrogen were applied to young Douglas-fir seedlings.


Treatment    N0    N1    N2    N3
    4.37    7.50    7.80    9.40
    6.72    8.80    7.82    9.28
    8.32    8.73    9.62
    8.03        9.00
a)    Construct the analysis of variance table (α = 0.05).
b)    Calculate 95% confidence limits for the mean of treatment N2.


3.    An experiment was set up to test the production of women against the production of men in forest inventory cruising. The data below show the number of plots they put in per day in three different forest types (A, B, C) for four randomly selected working days.