Answer:
a) Null hypothesis: 
Alternative hypothesis: 
And we have this property
The degrees of freedom for the numerator on this case is given by
where k =3 represent the number of groups.
The degrees of freedom for the denominator on this case is given by
.
And the total degrees of freedom would be
The mean squares between groups are given by:

And the mean squares within are:

And the F statistic is given by:

And the p value is given by:

So then since the p value is lower then the significance level we have enough evidence to reject the null hypothesis and we conclude that we have at least on mean different between the 3 groups.
b) 
The degrees of freedom are given by:

The confidence level is 99% so then
and
and the critical value would be: 
The confidence interval would be given by:


Step-by-step explanation:
Previous concepts
Analysis of variance (ANOVA) "is used to analyze the differences among group means in a sample".
The sum of squares "is the sum of the square of variation, where variation is defined as the spread between each individual value and the grand mean"
Part a
Null hypothesis: 
Alternative hypothesis: 
If we assume that we have
groups and on each group from
we have
individuals on each group we can define the following formulas of variation:
And we have this property
The degrees of freedom for the numerator on this case is given by
where k =3 represent the number of groups.
The degrees of freedom for the denominator on this case is given by
.
And the total degrees of freedom would be
The mean squares between groups are given by:

And the mean squares within are:

And the F statistic is given by:

And the p value is given by:

So then since the p value is lower then the significance level we have enough evidence to reject the null hypothesis and we conclude that we have at least on mean different between the 3 groups.
Part b
For this case the confidence interval for the difference woud be given by:

The degrees of freedom are given by:

The confidence level is 99% so then
and
and the critical value would be: 
The confidence interval would be given by:

