Assignment
1. A hospital keeps a record of the number of males and females in different age groups
who contract a particular disease. The data are summarized as follows:
Age Groups
10-25 26-40 41-55 56 +
____________________________________________
Male 23 34 64 29
Female 20 31 55 44
____________________________________________
a) Are gender and age of contracting the disease independent of one another (α ≤ .05)?
b) A researcher believes that people in the 41-55 age group are three times as likely to
develop the disease as are those in each of the two younger age groups, while those in the
56 + age group are only twice as likely (relative to those in the two youngest groups). The
two youngest age groups are not expected to differ from each other. Do the data support
these beliefs (α ≤ .01)?
c) It is also believed that, relative to males, the proportion of females in the 56 + age
group that develops the disease is significantly different from the proportion of females in
the 10-25 age group that develops the disease. Test this belief with α ≤ .05.
2. Fred is testing a large prize wheel which has the numbers one, two, three, and four
repeated along its circumference. When Fred spun the wheel 80 times, the wheel stopped
at a one 12 times, at a two 20 times, at a three 20 times, and at a four 28 times. Fred then
oiled the wheel and spun it an additional 120 times. This time he obtained frequencies of
12, 20, 32, and 56 respectively. Fred was careful to spin the wheel in the same manner
each time.
a) Does the wheel behave differently after being oiled? (α ≤ .05)
b) When the wheel is oiled, is the probability of occurrence of a number proportional to
the number (i.e., does the wheel stop at a two twice as often as at a one, etc.)? Use α ≤ .05.
3. There are still many local chapters of the Grateful Dead fan club throughout the
United States and Canada. Each chapter has 10 members and by coincidence the
gender composition of each is exactly the same: 7 males and 3 females. Each local
chapter sends a committee of 3 to the annual national convention. This year, the
composition of these committees is as follows:
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