Hypothesis tests for the
means are hypothesis
tests used to test the means
of samples in order to make inferences about
the means of the populations from which
they are drawn.
Parametric
tests (tests that rely on the
data conforming to a normal distribution)
include:
ttest 
comparing the mean
against a specified value using a sample
of 30 items or fewer 
Two
sample ttest 
comparing the means
of two samples of 30 items or fewer 
Paired
ttest 
comparing the means
of two samples of 30 items or fewer,
when the items in the two samples can
be 'paired' 
ztest 
comparing the the
mean against a specified value when
the sample has more than 30 items or
the standard deviation is known 
Nonparametric
tests for the mean include:
If there are more than two populations
the Analysis of Variance (ANOVA)
is used.
