Solving Multiple Questions on
Descriptive Statistics
1. Determine whether the
description corresponds to an observational study or an experiment.
Forty patients with skin cancer
are divided into two groups. One group an experimental drug to fight cancer, the
other a placebo. After two years, the spread of the cancer is measured.
Does the description correspond to
an observational study or experiment?
2. A worker assembles one item
every 20 minutes, so 120 items are completed in her first week of work. Her
manager checks her work by randomly selecting a day of the week, then reviewing
all the items she completed that day. Does the sampling plan result in a random
sample? Simple random sample?
Does this sampling plan result in
a random sample?
Does this sampling plan result in
a simple random sample?
3. Find the mean median mode and
midrange for the given sample data in millions of dollars. Given that these the
top 10 salaries, do we know anything about the salaries of TV personalities in
general? Are such top 10 lists valuable for gaining insight into the larger
population?
37.4 36 35.6 26.5 15.3 12.5 12.1
9.2 9.7 8
A. Mean___
B. Median____
C. Mode _____
D. Midrange_____
Given that these are the top 10
salaries, do we know anything about the salaries of TV personalities in
general?
Are such top 10 lists valuable for
gaining insight into the larger population?
4. A woman wrote to a newspaper
advice columnist and claimed that she gave birth 313 days after a visit from
her husband, who was in the Navy. Lengths of pregnancies have a mean of 267.6
days and a standard deviation of 15.5 days. Find the z score for 313 days. Is
such a length unusual?
The z score is ___
Is the pregnancy length of 313
days unusual?
5. Suppose a baseball player had
208 hits in a season. In the given probability distribution, the random
variable X represents the number of hits the player obtained in a game.
x 0 1 2 3 4 5
P(x) 0.1595 0.4758 0.2258 0.0872 0.0449 0.0068
a) Compute
and interpret the mean of the random variable X.
µx=____
What is a good interpretation of
the mean?
b) Compute
the standard deviation of the random variable X.
?x=____.
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