A scientist wishes to study the effects of nitrogen fertilizer and the types of water on lettuce production. Five types of nitrogen fertilizer at different level of ammonium nitrate, 0 g/m², 5 g/m², 10 g/m², 15 g/m² and 20 g/m² and two types of water, hard water and soft water, were applied to four replicate plots of land. The number of heads of lettuce harvested from the plot was recorded.
(a) Determine the experimental unit and the response variable in this experiment.
(b) List all the treatments in this study and state the levels of the treatments.
(c) Suggest a possible block for this study.
