Cengage Statistics Exam - PSY 346

For a complete frequency distribution, what is Σ(f/N)?

1

Given the following frequency table, which way is not correct for calculating ΣX? X= 1,2,3,4 f= 4,1,2,2,

1 + 2 + 3 + 4

What is the range for the set of scores: 7, 8, 11, 15, 17, 20?

13 OR 14

What score can be added to the following data set in order for the new median to be 12? 3,3,6,10,14,15,17

16

Which of the following sets of scores has the least variability

16, 17, 18, 19, 20

A survey asked families to report on the number of cars they own. The following is the frequency table for the results. X= 1,2,3 f= 125,101,? If the proportion of families with 1 car is 50%, find the number of families with 3 cars.

24

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.

3.2

In a data set the minimum element is 23, the maximum is 62, and the determined width is 4. Which of the following will not be an interval in the grouped frequency table?

32-36

Given the following set of sample scores, calculate the sample mean. 3,4,5,6,8,10

6

A teacher gave a quiz to her class of 30 students. However, she misplaced one of the quizzes. The teacher calculated the mean of the 29 quizzes to be μ = 68 points. At this point, the teacher found the missing quiz. On this quiz, the student scored 98 points. What is the mean for the class of all 30 students?

69

Given the following frequency distribution table, if all scores are increased by 5, what will the new mean be? X=1,2,3,4 F=5,3,3,1

7

A scientist collected a sample of data of cactus heights. The data was rounded to the nearest half foot. If the minimum score was 3.5 feet and the range was 4 feet, what was the maximum score?

7 FEET

A set of scores ranges from a high of X = 75 to a low of X = 23. If the bottom interval in a frequency table is 18-23, what is the top interval?

72-77

A scientist cannot read a data point in a list of weights of newborn babies. The report, however, notes that the median weight is 8.6. What is the missing weight? 7.6,8.1,---,8.8,8.8,8.9

8.4

Which of the following is a valid formula for calculating the sum of square deviations?

I AND II only SS=E(X-U)^2 SS=Ex^2- (Ex)^2 N

If we are looking at the average IQ of all Americans by looking at a sample of 50 people, which of the following is true? I. The average IQ of the sample could be greater than the average IQ of the population II. The average IQ of the sample could be smaller than the average IQ of the population. III. The average IQ of the sample must be the same as the average IQ of the population.

I and II only

Which is an example of a scientist being interested in a correlation? I. Determining the average height of males and females in England. II. Determining if there is a relationship between an insect's wingspan and its weight. III. Determining the average GPA in the freshman and senior classes at Valleyview High School.

II ONLY

Statistical techniques that allow us to study samples and then make generalizations about the populations from which they were selected are called what?

Inferential Statistics

The following frequency distribution table represents test scores for a class of students. How many students scored less than 70?

It cannot be determined.

Jerilyn calculated the percentages in a frequency table to be the following: 10%, 20.3%, 10%, 61.2%, and 24%. Which of the following is a true statement?

Jerliyn cannot be correct because her percentages add to more than 100%.

Two students, Lauren and Mary, are studying the average age at death of females in the town of Mobile, Alabama in the year 2011. They are able to obtain all of the female death records from Mobile for the year 2011. Lauren claims that this set of records represents the population for their study. Mary claims that it is only a sample. Who is correct, and why?

Lauren is correct because the study is only about female deaths in Mobile during 2011.

Which of the following can be determined from a grouped frequency distribution table?

N

A researcher is curious about the average age of drivers in the city of Columbus. If he obtains a database of every driver in the city and calculates the average, this is an example of a _________.

Parameter

Which of the following is a true statement?

Samples tend to be less variable than their populations.

A scientist is studying the effect of temperature on the ability of a plant to grow. She places four plants in environments of four different temperatures. All plants are given the same amount of water and light each day. She measures the height of each plant at the end of a month. Which of the following describes the dependent and independent variables?

The dependent variable is the plant heights; the independent variable is the room temperature.

Which of the following is not an appropriate definition of the mean?

The middle of all of the scores once they are ordered from least to greatest

In a study measuring the number of books read in a month, a group of data ranging from 0-6 is shown in a histogram. If the bars in the histogram gradually decrease in height from left to right, what can you conclude about the data set?

There are more people reading lower numbers of books than higher numbers.

If the median is removed from a data set, what can you determine about the new median?

There is nothing you can determine about the new median without knowing the list of scores.

Which of the following is true for the quantity ∑(X - μ)?

This is the sum of the deviations, and it is always 0.

Four species of insects around a pond are being studied. The initial phase of the study involves capturing and counting members of the species. The four species are labeled A, B, C, and D. If these values are presented in a frequency distribution graph, what kind of graph would be appropriate?

a bar graph

Statistical methods are classified into which two major categories?

descriptive and inferential

A researcher collected data on the number of traffic violations received by individuals younger than 30 years of age. The frequency distribution table displays the results of the data collection. X= 4,3,2,1,0 F= 13,71,71,82,101 To the nearest tenth, calculate the mean, median, and mode.

mean = 1.4, median = 1, mode = 0

A survey collected data on people's favorite type of movie. The following table lists the results. Genre= comedy, horror, action, romance f= 129 62 78 82

mode

A research study comparing salaries for recent college graduates in Spain versus France reports that recent graduates in France earn more than those in Spain. What research design did this study use?

nonexperimental

In what kind of study will you find a quasi-independent variable?

nonexperimental studies

Which of the following is not required for a proper experiment?

quasi-independent variable

The mean of a set of scores is μ = 125. If we remove the score 122 from the set, what will happen to the mean?

the mean will increase

When is the standard deviation of a set of scores equals to 0?

when the range of the scores is 0.

When is the population standard deviation greater than the population variance?

when the variance is less than 1

Find the population variance and standard deviation for the following ages of children in a family: 1, 3, 5, 7, 8, 11, 14.

σ = 4.17, σ2 = 17.43