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 differs in variability in the seventh month and 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

H0:

H1:

f0.025

F=

do we reject or not reject?