Question 2

In the jury pool available for this week, 30 percent of potential
 jurors are women. A particular trial requires that, out of a jury of
 12, at least three are women. If a jury of 12 is to be selected at
 random from the pool, what is the probability it meets the
 requirements of this trial? (A) (B) (C) (E) 0.168 0.843 0.915 The
 answer cannot be determined without know- ing the size of the jury

  • We cannot use a binomial model unless we know that the probability of drawing a woman for the pool is nearly constant.

  • However, since we are drawing 12 jurors without replacement, this is not necessarily true unless the jury pool is very large (at least 120)

    Requirements to be Binomial- B.I.N.S A binomial setting arises when
we preform several independent trials of the same chance process and
record the number of times that a particular outcome occurs. The four
conditions for a binomial setting are: Binary? The possible outcomes
of each trial can be classified as "success" or "failure" •
Independent? Trials must be independent; that is, knowing the result
of one trial must not have any effect on the result of any other trial
Number? The number of trials n of the chance process must be fixed in
advance. Success? On each trial, the probability p of success must be
the same.

Question 11

  • A discrete variable takes only a countable number of values. The number of test questions a student guesses the answers to is a random variable with possible values 0, 1, 2,…n, where n is the number of questions on the test.

    A discrete variable is a variable which can only take a countable
number of values. In this example, the number of heads can only take 4
values (0, 1, 2, 3) and so the variable is discrete. The variable is
said to be random if the sum of the probabilities is one. Probability
Density Function. Discrete Random Variables — Mathematics A-Level

    DIE ROLL • If I roll a die, what are the possible I can get?
outcomes • EXACTLY "1" • EXACTLY "2" • EXACTLY • EXACTLY • EXACTLY "5"
• EXACTLY • Only six outcomes

Question 29

  • If we take different samples from the same population, the estimates from the different samples will be different. The difference in percentages may be entirely due to sampling variation.


Question 30

In a clinical trial, 30 sickle cell anemia patients are randomly
 assigned to two groups. One group receives the currently mar- keted
 medicine, and the other group receives an experimental medicine. Each
 week, patients report to the clinic where blood tests are conducted.
 The lab technician is unaware of the kind of medicine the patient is
 taking. This design can be described as (A) a completely randomized
 design, with the currently mar- keted medicine and the experimental
 medicine as two treatments (B) a matched-pairs design, with the
 currently marketed medi- cine and the experimental medicine forming a
 pair (C) a randomized block design, with the currently marketed
 medicine and the experimental medicine as two blocks (D) a randomized
 block design, with the currently marketed medicine and the
 experimental medicine as two treatments (E) a stratified design with
 two strata, patients with sickle cell disease. forming one stratum and
 those without sickle cell disence forming the other stratum

  • This experiment consists of two treatments, the currently marketed medicine and the experimental medicine. Patients are not matched, and no blocks are formed. Only patients with sickle cell disease are involved in the experiment.

Question 31

  • Confidence intervals are constructed as Statistic ± Margin of Error.

  • Therefore, the statistic is always right in the center of the confidence interval.

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