I want to learn statistical functions in excel and mathematical terms from the following question with good explanation.

I am conducting a study on how benzene , the active ingredient in soke,weed etc. for cancer causing. There are 4 groups in this study. After two weeks of either smoking mairjuana, ingesting THC pills, eating marijuana brownies, or taking a placebo control they are given a physics exam. The results of the exam are given below:

Smoke	Pills	Brownies	Control
59	72	69	71
68	66	67	72
88	68	94	71
62	65	75	65
71	83	85	80
66	61	79	80
75	91	87	64
91	75	85	72
74	74	92	71
72	59	75	74
66	68	91	70
68	88	74	90
65	62	72	71
83	71	66	65
61	94	83	91
91	75	87	80
75	91	85	64
74	74	92	72

(1) What are the appropriate null and alternative hypotheses for this study?

(2) Find "ANOVA Single Factor" Select the correct data range and set alpha =0.05.What is the p-value for the ANOVA?

(3) Should I reject the null hypothesis at alpha = 0.05? What is the conclusion ?

(4) After performing the ANOVA analysis, is there any further analysis to do?if so then what it is

(5) Why is it called "Analysis of *Variance*" if we are comparing *means*?