1: What is the best explanation for why a normal distribution is only an approxi
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Question
1: What is the best explanation for why a normal distribution is only an approximation for a binomial distribution?
a. Binomial values are discrete, and normal values are continuous.
b. The means for the two distributions are different.
c. The standard deviations for the two distributions are different.
d. There are more outcomes in a normal distribution than in a binomial distribution.
A researcher studies the factors that determine the number of cars owned by American families. The variable, number of cars, is an example of a___________ variable.
a. discrete b. continuous c. nominal d. ordinal
A researcher selects all of the possible samples with n = 7 scores from a population and computes the sample variance, dividing by n – 1, for each sample. If the population variance is ?2 = 9, then what is the average value for all of the sample variances?
a. 9
b. greater than 9
c. less than 9
d. impossible to determine
A teacher has given a test to a group of students. The set of scores is: 78, 79, 79, 81, and 83. Find the population variance for this group of tests.
a. 2.24 b. 3.2 c. 5 d. 80
Which of the following is not an assumption for hypothesis testing using the t statistic?
a. The population sampled must be normal.
b. The values in the sample must consist of independent observations.
c. The sample size must be greater than 30.
d. The population standard deviation is unknown.
What is the advantage of a repeated-subject research study?
a. It uses exactly the same individuals in all treatment conditions.
b. There is no risk that the participants in one treatment are substantially different from the participants in another
c. A smaller number of subjects is required.
d. All a, b, and c.
Which of the following is not required for a proper experiment?
a. a control condition
b. an experimental condition
c. two variables
d. a quasi-independent variable
When a linear regression is obtained for X, Y and residuals are computed for Y, what is the sum of these residuals?
a. 0 b. 1 c. The mean of the Y values d. Twice the mean of the Y values
A researcher was asked to provide the standard deviation for a sample of fish weights. The researcher originally reported a standard deviation of 12.3 grams. However, upon closer investigation, she discovered that her scale was 1.1 grams off and that each fish was actually 1.1 grams heavier than originally reported. What is the new standard deviation?
a. 12.3 b. 13.4 c. 15.53 d. It is impossible to tell without knowing the original weights.
A calculus exam has a mean of µ = 73 and a standard deviation of ? = 4. Trina's score on the exam was 79, giving her a Z-score of +1.50. The teacher standardized the exam distribution to a new mean of µ = 70 and standard deviation of ? = 5. What is Trina's Z-score for the standardized distribution of the calculus exam?
a. z = +2.25 b. z = +.50 c. z = +.75 d. z = +1.50
Explanation / Answer
d. “There are more outcomes in a normal distribution than in a binomial distribution.”
a. discrete (“The word discrete means countable”)
c. less than 9
b. 3.2
The formula for the variance of an entire population is:
where N is the population size and ? is the population mean.
c. The sample size must be greater than 30.
d. All a, b, and c.
a. a control condition
a. 0 “ The mean of the predicted values (Y') is equal to the mean of actual values (Y), and the mean of the residual values (e) is equal to zero.”
a. 12.3
Because the mean increases by the same amount.
If yi=xi+A
then y¯¯¯=x¯¯¯+A
s2y=1n?i=1n(yi?y¯¯¯)2
=1n?i=1n((xi+A)?(x¯¯¯+A))2
d. z = +1.50 “ After scores in a distribution are standardized, the revised z scores are always the same as the original z scores”
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