A researcher knows that the average heart rate in the
population is 72 beats/minute. He is interested in
determining if people who walk at a moderate rate
every day have lower heart beats. He selects 15
walkers and finds that the average heartbeat among his
sample is 69 beats/minute with a standard deviation of
8.6beats. What conclusion can he draw and why?
A researcher knows that the average heart rate in the
population is 72 beats/minute. He is interested in
determining if people who walk at a moderate rate
every day have lower heart beats. He selects 15
walkers and finds that the average heartbeat among his
sample is 69 beats/minute with a standard deviation of
8.6 beats. What conclusion can he draw and why?
1) Determine what you know:
  72
X  69
s  8.6
A researcher knows that the average heart rate in the
population is 72 beats/minute. He is interested in
determining if people who walk at a moderate rate
every day have lower heart beats. He selects 15
walkers and finds that the average heartbeat among his
sample is 69 beats/minute with a standard deviation of
8.6 beats. What conclusion can he draw and why?
2) Choose formula:
No standard deviation of the population
This means a t test for single sample.
A researcher knows that the average heart rate in the
population is 72 beats/minute. He is interested in
determining if people who walk at a moderate rate
every day have lower heart beats. He selects 15
walkers and finds that the average heartbeat among his
sample is 69 beats/minute with a standard deviation of
8.6 beats. What conclusion can he draw and why?
3) Write hypothesis statements
H 0 :   72
H1 :   72
A researcher knows that the average heart rate in the
population is 72 beats/minute. He is interested in
determining if people who walk at a moderate rate
every day have lower heart beats. He selects 15
walkers and finds that the average heartbeat among his
sample is 69 beats/minute with a standard deviation of
8.6 beats. What conclusion can he draw and why?
4) Compute t value
a) Compute standard error estimated
S
SX 
n
S
SX 
n
SX 
8.6
15
8 .6
SX 
3.87
S X  2.22
X 
t
SX
69  72
t
2.22
3
t
2.22
t  1.35
H 0 :   72
H1 :   72
df = 14
critical value = 2.145
Conclusion: Accept the null hypothesis. This sample is not
significantly different from the whole population.
This means: That moderate walking was not
shown to have an effect.
Another researcher is interested in a similar question.
She asks whether people who do aerobic exercise at
least three times per week have lower heart beats. She
selects 15 exercisers and finds that the average
heartbeat among this sample is 67 beats/minute with a
standard deviation of 8.6 beats. What conclusion can
she draw and why?
Another researcher is interested in a similar question.
She asks whether people who do aerobic exercise at
least three times per week have lower heart beats. She
selects 15 exercisers and finds that the average
heartbeat among this sample is 67 beats/minute with a
standard deviation of 8.6 beats. What conclusion can
she draw and why?
X  67
All other values remain the same.
X 
t
SX
67  72
t
2.22
5
t
2.22
t  2.24
H 0 :   72
H1 :   72
df = 14
critical value = 2.145
Conclusion: Reject the null hypothesis. This sample is
significantly different from the whole population.
This means: That aerobic exercise appears to
have an effect of lowering heart rate.