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8.1 Exercise #25

The mean ACT score for 43 male high school students
is 21.1 and the standard deviation is 5.0. The mean
ACT score for 56 female high school students is 20.9
and the standard deviation is 4.7.
At   0.01, can you reject the claim that male and
female high school students have equal ACT scores?
8.1 Stuff

Two samples are independent if the sample
selected from one population is not related to the
sample selected from the second population.

Two samples are dependent if each member of
one sample corresponds to a member of the other
sample. Dependent samples are also called paired
samples or matched samples.
8.1 Exercises

Sample 1: The IQ scores of 60 females.
Sample 2: The IQ scores of 60 males.

Sample 1: The SAT scores of 44 high school
students.
Sample 2: The SAT scores of the same 44 high
school students after taking an SAT prep course.
8.1 Exercise #25

The mean ACT score for 43 male high school students
is 21.1 and the standard deviation is 5.0. The mean
ACT score for 56 female high school students is 20.9
and the standard deviation is 4.7.
At   0.01, can you reject the claim that male and
female high school students have equal ACT scores?
8.1 Stuff
1) The samples must be randomly selected.
2) The samples must be independent.
3) Each sample size must be at least 30 or, if not,
each population must have a normal distribution
with a known standard deviation.
8.1 Stuff

The sampling distribution for x1  x2 is a normal
distribution with mean and standard deviation of
 x  x   x   x  1   2
1
2
1
2
and
 x x   x 2   x 2 
1
2
1
2
 12
n1

 22
n2
8.1 Exercise #25

There is insufficient evidence at the 1% level to
reject the claim that male and female high school
students have equal ACT scores.