151
The values can be seen by changing to the NUM view.
In the MATH menu, Probability section, there is
a function called UTPC (Upper-Tailed
Probability Chi-squared) which will give the
critical X
2
probability for a supplied number of
degrees of freedom and a value. See page
283. In this case we would like the value for a
given probability so we will enter the formula into the Solve aplet.
Change to the NUM view, enter the known
parameters of D=4 and P=0.05, and
for
the critical X
2
value.
Since our value of 16.387 is larger than the critical value of 9.488 we
conclude that we must reject the null hypothesis and judge that the observed
values do not follow this binomial distribution and hence that the coin is
probably biased. This does not say that it is not binomially distributed; just
not with those parameters.
As can be seen from this example, the Statistics and Solve aplets can be
used for simple problems, particularly in cases where working is required to
be shown. For more complex problems the Inference aplet provides more
powerful tools.
Hypothesis test: T-Test 1-
µ
A company makes boxes of matches which
are supposed to contain an average of 50
matches. A student has counted the contents
of 20 boxes and found the results below.
Using a 5% confidence level, decide whether
the claim is correct.
47, 50, 52, 51, 53, 51, 49, 49, 52, 53, 54, 48, 53, 55, 52, 54, 54, 53, 48, 48
Enter the data into the Statistics aplet then change to the Inference aplet.
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