Download Quia Quiz – After Unit 6 Which is true? Random scatter in the

Quia Quiz – After Unit 6
1. Which is true?
I. Random scatter in the residuals indicates a model with high predictive power.
II. If two variables are very strongly associated, then the correlation between them will be near +1.0 or -1.0.
III. The higher the correlation between two variables the more likely the association is based in cause and
effect.
A) none
B) I only
C) ll only
D) I and ll
E) I, ll, and IIl
2. A regression analysis of students’ college grade point averages (GPAs) and their high school GPAs found R2 =
0.311. Which of these is true?
I. High school GPA accounts for 31.1% of college GPA.
II. 31.1% of college GPAs can be correctly predicted with this model.
III. 31.1% of the variance in college GPA can be accounted for by the model
A) I only
B) II only
C) III only
D) I and II
E) None
3. A Random Variable(X) has a mean of 43 with a standard deviation of 8.5. Another Random Variable(Y)
independent of the first has a mean of 23 with a standard deviation of 6.6. If we subtract X – Y, what is the new
mean and standard deviation of the resulting random variable?
A) mean = 66; st. dev. = 15.1
B) mean = 20; st. dev. = 15.1
C) mean = 20; st. dev. = 1.9
D) mean = 20; st. dev. = 10.76
E) mean = 20; st. dev. = 5.36
4. The distribution of the ages of all the coins in Mr. Wheeles’s extra large piggy bank is skewed right with a mean
of 3.6 years and st. dev. of 1.9 years. His daughter takes out a handful of coins(after mixing them up really well)
and gets 32 coins. What would be the resulting distribution from the sample mean age of the coins?
A) Skewed Right Mean = 115.2 years
St. Dev. = 60.8 years
B) Skewed Right Mean = 3.6 years
St. Dev. = 1.9 years
C) Skewed Right Mean = 3.6 years
St. Dev. = 0.34 years
D) Symmetric
Mean = 3.6 years
St. Dev. = 1.9 years
E) Symmetric
Mean = 3.6 years
St. Dev. = 0.34 years
5. P(A) = 0.39 P(B|A) = 0.42 P(B) = 0.22. What is P(A or B)?
A) 0.1638
B) 0.19
C) 0.4462
D) 0.61
E) 0.81
6. In a game 6 standard 6-sided dice are rolled. What is the probability that you would roll at least 3 5’s?
A) 0.0087
B) 0.0536
C) 0.0623
D) 0.1667
E) 0.9913
7. From a sample of 200 randomly selected people a one proportion z-interval was found to be (0.3098, 0.4702).
What level of confidence was used here?
A) 90%
B) 92%
C) 95%
D) 98%
E) 99.9%
8. It is thought that 34% of all people have a certain genetic marker. A random sample of 88 people from an
isolated town of 1300 residents is taken and it is found that 22 have the genetic marker. Which of the following
is the correct conclusion?
A) There is significant evidence that the proportion of people from the town that have the genetic marker is
different than 34% at a level of significance of 5%.
B) There is significant evidence that the proportion of people from the town that have the genetic marker is
different than 34% at a level of significance of 1%.
C) There is significant evidence that the proportion of people from the town that have the genetic marker is
less than 34% at a level of significance of 5%.
D) There is significant evidence that the proportion of people from the town that have the genetic marker is
less than 34% at a level of significance of 1%.
E) Nothing can be concluded since the conditions were not met for inference.
9. Which of the following are resistant to outliers.
I.
II.
III.
IV.
V.
Standard deviation
Range
IQR
Mean
Median
A) I, II, and V
B) III and V
C) I and V
D) II and IV
E) I, III, and V
10. A study of human development showed two types of movies to groups of children. Crackers were available in a
bowl, and the investigators compared the number of crackers eaten by children watching the different kinds of
movies. One kind of movie was shown at 8 AM (right after the children had breakfast) and another at 11 AM
(right before the children had lunch). It was found that during the movie shown at 11 AM, more crackers were
eaten than during the movie shown at 8 AM. The investigators concluded that the different types of movies had
an effect on appetite. The results cannot be trusted because
A) the study was not double-blind. Neither the investigators, nor the children should have been aware of
Which movie was being shown
B) the investigators were biased. They knew beforehand what they hoped the study would show
C) the investigators should have used several bowls, with crackers randomly placed in each
D) the time the movie was shown is a confounding variable. .