Frozen computer: A computer system administrator noticed that computers running a particular operating system seem to freeze up more often as the installation of the operating system ages. She measures the time (in minutes) before freeze-up for

6

computers one month after installation and for

6

computers seven months after installation. The results are shown. Can you conclude that the time to freeze-up is more variable in the seventh month than the first month after installation? Let

1

denote the variability in time to freeze-up in the first month after installation. Use the

=0.05

level and the critical value method with the table.

One month:	245.3	207.4	233.1	215.9	235.1	225.6
Seven months:	149.4	156.4	103.3	84.3	53.2	127.3

State the null and alternate hypothesis.

:H0
:H1

This is a right-tailed test.

₁

₂

Find the critical value. Round the answer to two decimal places.

The critical value f0.05 is .

Compute the test statistic. Round the answer to two decimal places.

=F

Determine whether to reject

H0

.

Reject the null hypothesis H0 .

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State a conclusion.

There is not enough evidence to conclude that the time to freeze-up is less variable in the seventh month than in the first month after installation.