Recycling newsprint is important in reducing waste. The article "The Influence of Newspaper Aging on Optical Properties of its De-inked Pulp" (M. Rahmaninia, A Latibari, et al., Turkish J Eng Env Sci, 2008:35-39) presents the results of an experiment to determine the effects of the age of newsprint on the brightness (in percent) of the recycled paper. Four aging periods were considered, along with five concentrations of sodium hydroxide (NaOH), used to de-ink the paper. The effect of the sodium hydroxide concentration is not of interest. The results are presented in the following table.

a. Identify the blocking factor and the treatment factor.
b. Construct an ANOVA table. You may give ranges for the P-values.
c. Can you conclude that brightness differs with age? Explain.
d. Which pairs of ages, if any, can you conclude to have differing brightnesses? Use the 5% level.

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NaOH Concentration Age (Months) 0 4 8 12 096 54.6 45.6 46.1 44.0 0.5% 54.3 44.1 45.9 44.1 1% 55.5 43.7 46.4 45.2 1.5% 56.3 45.6 45.0 43.7 2% 56.6 47.1 47.9 46.5