Stat CH5 Test Questions with Correct Answers
A Gallup poll of 1236 adults showed that 12% of the respondents believe that it is bad luck to walk under a ladder. Consider the probability that among 30 randomly selected people from the 1236 who were polled, there are at least 2 who have that belief....
A Gallup poll of 1236 adults showed that 12% of the respondents believe that it is bad
luck to walk under a ladder. Consider the probability that among 30 randomly selected
people from the 1236 who were polled, there are at least 2 who have that belief. Given
that the subjects surveyed were selected without replacement, the events are not
independent. Can the probability be found by using the binomial probability formula?
Why or why not? - Answer-Yes. Although the selections are not independent, they can
be treated as being independent by applying the 5% guideline.
Based on a survey, when 1009 consumers were asked if they are comfortable with
drones delivering their purchases, 42% said yes. The probability of randomly selecting
30 of the 1009 consumers and getting exactly 24 who are comfortable with the drones is
represented as 0plus. What does 0plus indicate? Does 0plus indicate that it is
impossible to get exactly 24 consumers who are comfortable with drones? - Answer-
The probability 0plus indicates that the probability is a very small positive value. It
indicates that the event is possible, but very unlikely.
Which of the following is not a requirement of the binomial probability distribution? -
Answer-The trials must be dependent.
If calculations are time-consuming and if a sample size is no more than 5% of the size
of the population, the _______ states to treat the selections as being independent (even
if the selections are technically dependent). - Answer-If calculations are time-consuming
and if a sample size is no more than 5% of the size of the population, the
5% Guideline for Cumbersome Calculations
states to treat the selections as being independent (even if the selections are
technically dependent).
In the binomial probability formula, the variable x represents the _______. - Answer-In
the binomial probability formula, the variable x represents the
number of successes.
Which of the following is NOT one of the three methods for finding binomial probabilities
that is found in the chapter on discrete probability distributions? - Answer-Use a
simulation
For the binomial distribution, which formula finds the standard deviation? - Answer-//npq
, A main goal in statistics is to interpret and understand the meaning of statistical values.
The _______ can be very helpful in understanding the meaning of the mean and
standard deviation. - Answer-A main goal in statistics is to interpret and understand the
meaning of statistical values. The
Range Rule of Thumb
can be very helpful in understanding the meaning of the mean and standard deviation.
Identify the expression for calculating the mean of a binomial distribution. - Answer-np
Based on a survey, assume that 59% of consumers are comfortable having drones
deliver their purchases. Suppose we want to find the probability that when four
consumers are randomly selected, exactly two of them are comfortable with the drones.
What is wrong with using the multiplication rule to find the probability of getting two
consumers comfortable with drones followed by two consumers not comfortable, as in
this calculation: left parenthesis 0.59 right parenthesis left parenthesis 0.59 right
parenthesisleft parenthesis 0.41 right parenthesis left parenthesis 0.41 right
parenthesisequals0.0585? - Answer-There are other arrangements consisting of two
consumers who are comfortable and two who are not. The probabilities corresponding
to those other arrangements should also be included in the result
The accompanying table describes results from groups of 8 births from 8 different sets
of parents. The random variable x represents the number of girls among 8 children.
Complete parts (a) through (d) below. - Answer-c. Since the probability of getting 7 or 8
girls includes getting 6 girls, the result from part (b) is the relevant probability.
d. No, since the appropriate probability is greater than 0.05, it is not a significantly high
numbe
The accompanying table describes results from groups of 8 births from 8 different sets
of parents. The random variable x represents the number of girls among 8 children.
Complete parts (a) through (d) below.
Find the probability of getting exactly 1 girl in 8 births. - Answer-c. Since getting 0 girls is
an even lower number of girls than getting 1 girl, the result from part (b) is the relevant
probability.
d. Yes, since the appropriate probability is less than 0.05, it is a significantly low
number.
The table to the right lists probabilities for the corresponding numbers of girls in three
births. What is the random variable, what are its possible values, and are its values
numerical? - Answer-The random variable is x, which is the number of girls in three
births. The possible values of x are 0, 1, 2, and 3. The values of the random value x are
numerical.
Is the random variable given in the accompanying table discrete
or continuous? Explain. - Answer-The random variable given in the accompanying table
is
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