1. Based on the properties of normal distribution, which of the following is correct?

Group of answer choices

The letter grade of students in a large class roughly follows a normal distribution

Symmetric data follow a normal distribution

The household income of all the families in California roughly follows a normal distribution

Bimodal data do not follow a normal distribution

2. Are the following statements true or false? In a sample, we are bound to make mistakes when we use X to estimate .

In a sample, we can use Xto estimate because random sampling guarantees X= in this sample.

In inferential statistics, we usually care how well we do in a given sample more than our overall performance in the long term.

Group of answer choices

Only is true

Both and are true

Both and are true

Only is true

Both and are true

3. A researcher tries to demonstrate that a new instructional technique will improve the mean academic performance of college students. In this case, the null hypothesis should be:

Group of answer choices

mean academic performance will decrease or remain the same

mean academic performance will increase

mean academic performance will decrease

mean academic performance will not change

4. In a scatterplot, all the data points closely cluster around a straight line. Then there is _____________ correlation between the two variables.

Group of answer choices

negative

positive

weak

strong

5.

Suppose the correlation coefficient between X and Y is r=0.03. Then what can we conclude? Perhaps there is still a pattern in the relationship between X and Y, but a straight line fails to capture that pattern. The scattorplot of X and Y must be one that shows no pattern at all. How Y changes must be irrelevant to how X changes.

Group of answer choices

Both and are true

Both and are true

Only is true

Only is true

Only is true

6.

Which of the following correlation coefficient represents the strongest relationship between two variables?

Group of answer choices

r = -0.5

r = -0.80

r = 1.30

r = 0.20

r = 0.65

7.

Exam scores of a very easy test follow a negatively skewed distribution. These scores have = 50 and = 15. Eric got 61 on this exam. Which of the following statements must be correct?

Group of answer choices

50% of the class got scores above 50.

Eric did better than 73% of his classmates

there is not enough information to calculate probabilities

Eric did better than 76.73% of his classmates.

8.

Consider the following two statements. Are they true or false?

The correlation r=0means there is no linear relationship The correlation is stronger in the case r=0 than in the case r=0.4.

Group of answer choices

Only is true

Only is true

Both and are false

Both and are true

9.

SAT scores in the population follow a normal distribution with standard deviation= 110. A researcher collects a random sample ofn= 121 students and found the sample mean SAT score isX=450. He then computes a 70% confidence interval for the population mean. What is the lower limit of this 70% confidence interval?

10.

In a sample of size n = 8, if we wish to form a 90% confidence interval using t-distribution, what is the t-score we should use in the confidence interval formula?

11.

Are the following two statements about hypothesis testing true or false?

The null hypothesis is a statement of being null in something--- that is, it always states there is no difference, no effect, no relationship, etc. The alternative hypothesis is superior to the null hypothesis, because we always try to demonstrate the former but reject the latter.

Group of answer choices

Only is true

Both and are true

Both and are false

Only is true

12.

If raw scores X follow a normal distribution, their z-scores will follow a __________ distribution.

Group of answer choices

symmetric but not necessarily normal

normal

normal but not necessarily standard normal

standard normal

13.

In the standard normal distribution, ___________% (percent) of data are above the z-score 1.40.

Put your answer in percentage, not proportions. If your answer is "12.34%" then put "12.34" in the blank.

14.

SAT scores follow N(500, 110). Eric is on the 20^thpercentile. What is Eric's SAT score?

15.

The normal distribution with = 1 and = 1 is _____________

Group of answer choices

the standard normal distribution

the perfect normal distribution

the ideal normal distribution

a regular normal distribution