This is my question.

An environmental epidemiologist has designed an experiment to test whether the claims of a chemical company that states that two of the company's new chemical compounds have no harmful effect on humans nor living being is true. For this, the epidemiologist takes 12 male rats, divides them into 3 groups of 4, and puts them in 3 chambers: one where no chemical was added to the air, and 2 chambers where 2 different chemical compounds are dissolved in the air, one per chamber, at a low concentration for 24 hours a day for multiple days. After 15 days, the epidemiologist measures blood pressure in the rats. She is interested in assessing whether being exposed to the chemical compounds changes blood pressure in the rats. The table below provides the data and summary statistics. Observation 1 2 3 4 No chemical 107.7 107.3 108.5 105.9 107.4 46099.6 1.2 Chemical 1 122.3 126.9 125.0 113.7 122.0 59613.6 34.0 Chemical 2 102.2 116.8 111.2 117.5 111.9 50258.8 50.0 y. =113.8; SST=703.3 and SSE=255.5. (a) [5 pts] State the null and the alternative hypothesis that the epidemiologist wants to assess. Write at least the null hypothesis in mathematical form. (b) [10 pts] The epidemiologist wants to use ANOVA to analyze the data she has collected. What are the assumptions that have to be satisfied in order to use ANOVA? Do you believe they can hold here? (c) [5 pts] Calculate SSTr