A newborn baby has extremely low birth weight (elbw) if it weighs less than 1000 grams. a study of the health of such children i
n later years examined a random sample of 219 children. their mean weight at birth was x = 810 grams. this sample mean is an unbiased estimator of the mean weight μ in the population of all elbw babies. this means that
<span>11.2 Florida voters. Florida played a key role in the 2000 and 2004 presidential elections. Voter
registration records in August 2010 show that 41% of Florida voters are registered as Democrats
and 36% as Republicans. (Most of the others did not choose a party.) To test a random digit
dialing device that you plan to use to poll voters for the 2010 Senate elections, you use it to call
250 randomly chosen residential telephones in Florida. Of the registered voters contacted, 34%
are registered Democrats. Is each of the boldface numbers a parameter or a statistic?
Answer
41 % of registered voters are Democrats: parameter
36% of registered voters are Republicans: parameter
34% of voters contacted are Democrats: statistic
11.7 Generating a sampling distribution. Let’s illustrate the idea of a sampling distribution in
the case of a very small sample from a very small population. The population is the scores of 10
students on an exam:
The parameter of interest is the mean score ÎĽ in this population. The sample is an SRS of size n =
4 drawn from the population. Because the students are labeled 0 to 9, a single random digit from
Table B chooses one student for the sample.
(a) Find the mean of the 10 scores in the population. This is the population mean ÎĽ.
(b) Use the first digits in row 116 of Table B to draw an SRS of size 4 from this population.
What are the four scores in your sample? What is their mean ? This statistic is an estimate of
ÎĽ.
(c) Repeat this process 9 more times, using the first digits in rows 117 to 125 of Table B. Make a
histogram of the 10 values of . You are constructing the sampling distribution of . Is the
center of your histogram close to ÎĽ?
Answer
(a) ÎĽ = 694/10 = 69.4.
(b) The table below shows the results for line 116. Note that we need to choose 5 digits because
the digit 4 appears twice.
(c) The results for the other lines are in the table; the histogram is shown after the table.</span>
The reason both of these are valid scientific hypotheses is because A) scientists with different educational backgrounds may put forth different hypotheses to explain the same data. This approach in science is vital in making progress and has helped to explain many phenomena in the past. When scientists explain data using different approaches, they come to a more comprehensive conclusion.
Answer: Cells are the basic building blocks of all living things. Cells form structures to create tissue that makes up our bodies, plants, and animals.
