ANOVA

An experiment was performed to determine whether
chemical additives could reduce the NOX emissions
of cars on the road. There were four additives being
compared (the first additive is a neutral control).
The experiment involved filling up a car with 
additive-enriched fuel, driving a certain distance, 
and measuring the NOX levels produced (this involved
adding a clunky appendage to the car). Four cars were
used, and each car was run once with each additive.
The results are given below.

		Car
		1 2 3 4
	----------------
Additive:
	I 	21 26 20 35
	II	23 26 20 37
	III	13 11 14 24
	IV	17 15 20 30

a) Produce an ANOVA table for the above data,
with rows for the effect of Car and Additive.
b) What amount of emissions would you predict
if you didn't know which car or additive was
being used?
c) What amount of emissions would you predict
for Car 2 if you didn't know what additive was
used?
d) What amount of emissions would you predict
for Additive II if you didn't know what car was
used?
e) What level of emissions would you predict
for Car 2 and Additive II together?
f) Are the additives equivalent? If not, is there one
additive that reduces emisssions significantly?
g) How would your answer to f) be different if
we had not been told that different cars were used, 
so that we only knew that four measurements had
been made with each additive?