A biologist is interested in studying the effect of growth-enhancing nutrients and different salinity (acid) levels in water on the growth of shrimps. The biologist has ordered a large shipment of young tiger shrimps from a supply house for use in the study. The experiment is to be conducted in a laboratory where 120 tiger shrimps are placed randomly into each of 6 similar tanks in a controlled environment. The biologist is planning to use 3 different growth-enhancing nutrients (A, B, and C) and two different salinity levels (low and high).

1. How many treatment combinations are there that the biologists plan to use in the experiment. List the treatment combinations.
2. Using the treatments listed in part (a), describe a completely randomized design that will allow the biologists to compare the shrimps' growth after three weeks.
3. Give one statistical advantage to having only tiger shrimp in the experiment.
4. Give one statistical disadvantage to having only tiger shrimp in the experiment and why it's a disadvantage.