Variables
1 Variable Data
Probabilities in a Normal Distribution
Regression Analysis
Random Trivia
100
A school counselor records the following information for each senior: GPA, number of college applications submitted, and intended major.
Identify the observational unit(s) and the variable(s) of this study.
Observational units - seniors
Variables - GPA, number of college applications submitted, and intended major
100
In a bag of 20 skittles, there were 8 red skittles. Calculate the relative frequency of red skittles.
8/20 = 0.4
100
A research study tested the lifetime of a large sample of batteries. The mean lifetime was 255.5 minutes, with a standard deviation of 25.4 minutes. Find the z-score for a battery with a lifetime of 280 minutes.
z = 0.965
100
True or false: A point with a large residual is always an outlier.
False
100
Which planet in our solar system is known as the "Red Planet" due to the iron oxide (rust) on its surface?
A. Venus
B. Jupiter
C. Mars
D. Saturn
C. Mars
200
A researcher records the time (in seconds) it takes for laboratory mice to navigate a standardized maze. How should the variable "time to complete the maze" be classified?
A. categorical
B. quantitative, continuous
C. quantitative, discrete
D. explanatory
B. quantitative, continuous
200
A rope manufacturer tests a sample of 30 ropes and records each's breaking strength in newtons (N). The breaking strength vary from 1,100N to 2,075N. Which type of graph would best display the distribution of the sample data?
A. Pie chart
B. Bar chart
C. Frequency histogram
D. Frequency table
C. Frequency histogram
200
Find P(z<-1.68)
.0465
200
Researchers found the correlation between grouping behavior of deer and percent of woodland in the region to be -0.67. Interpret this value.
There is a moderate, negative relationship between grouping behavior of deer and percent of woodland in the region.
200
Before becoming a pioneer of modern data visualization and nursing, which famous historical figure famously drew "coxcomb" diagrams (polar area charts) to prove that more soldiers were dying from poor sanitation than from battlefield wounds?
A. Clara Barton
B. Florence Nightingale
C. Marie Curie
D. Eleanor Roosevelt
B. Florence Nightingale
300
A corporate health research team investigates the impact of introducing adjustable standing desks in a large office. Over a six-month period, they track the daily average typing speed (words per minute), reported fatigue levels (on a 1-10 scale), and resting heart rate of 200 employees. They also record each employee's baseline daily caffeine intake and average hours of sleep per night to account for potential confounding. The researchers specifically want to determine if the implementation of the standing desk causes a change in employee fatigue levels. In the context of this specific research question, what are the explanatory and response variables?
Explanatory - Type of desk (standing vs. regular)
Response - Reported level of fatigue
300
A random sample of golf scores give the following summary statistics: n=20, xbar=84.5, s=11.5, min=68, Q1=78, Median=86, Q3=91, max=112.
Determine if there are any outliers present.
112 is an outlier.
300
Find P(-0.84<Z<1.26)
.6957
300
A linear model was created to predict the concentration of zinc(ppm) from the concentration of lead(ppm) found in fish from a certain river. In the model, the slope is 19.0. Interpret this value.
For every 1ppm increase in the concentration of lead, the predicted concentration of zinc will increase by 19ppm.
300
Which country has the most natural lakes in the world, containing over half of all the natural lakes on Earth?
A. United States
B. Russia
C. Brazil
D. Canada
D. Canada
400
Data was collected on 20 students in an AP Statistics course. Which of the following is NOT an appropriate variable for the data set representing the 20 students?
A. age
B. gender
C. address
D. number of students in the data set
D. number of students in the data set
400
Describe the distribution of the stem and leaf plot.
The distribution of number of birds at a water hole each hour is skewed right with no apparent outliers. The number of birds vary from 13 to 67 and the median number of birds is 24.
400
A test of reading ability is normally distributed with a mean of 75 and a standard deviation of 10. What score represents the 90th percentile?
87.85
400
At a large airport, data were recorded for one month on how many baggage items were unloaded from each flight upon arrival as well as the time required to deliver all the baggage items on the flight to the baggage claim area. A scatterplot of the two variables indicated a strong, positive, linear association between the two variables. Which of the following statements is the best interpretation of the word "strong," in the description?
A. A least-squares model predicts that the more baggage items that are unloaded from a flight, the greater the time required to deliver the items to the baggage claim area.
B. The actual time required to deliver all the items to the baggage claim area based on the number of items unloaded will be very close to the time predicted by a least-squares model.
C. The time required to deliver an item to the baggage claim area is relatively constant, regardless of the number of baggage items unloaded from a flight.
D. The variability in the time required to deliver all items to the baggage claim area is about the same for all flights, regardless of the number of items unloaded from a flight.
B. The actual time required to deliver all the items to the baggage claim area based on the number of items unloaded will be very close to the time predicted by a least-squares model.
400
Before it became a massive global streaming platform, Netflix launched in 1997 as a DVD-by-mail service. What was the very first movie ever wrapped in a red envelope and mailed out to a customer?
A. Titanic
B. Pulp Fiction
C. Toy Story
D. Beetlejuice
D. Beetlejuice
500
An epidemiologist is designing a database for tracking a regional disease outbreak. Which of the following data collection fields yields categorical (nominal) data, even though it is inputted, stored, and displayed entirely as a sequence of numbers?
A. The patient's reported number of household members living under the same roof.
B. The patient's pain rating on a visual analog scale measured from 0 to 100 millimeters.
C. The 4-digit numerical routing code assigned to the external diagnostic laboratory processing the biological sample.
D. The sequential day of the year (1 through 365) on which the patient's primary symptom onset occurred.
C. The 4-digit numerical routing code assigned to the external diagnostic laboratory processing the biological sample
500
Data was collected by two different manufacturers on the lifespan of light bulbs, in thousands of hours. Compare the distributions of data from Manufacturer A and Manufacturer B.
The distribution of the life span of light bulbs from Manufacturer A is skewed left, whereas the distribution from Manufacturer B is approximately symmetrical. Neither distribution shows any apparent outliers. The median for Manufacturer B is 5, which is greater than the median for Manufacturer A (4). The distribution of life span of light bulbs from Manufacturer B shows greater variability with an IQR of 6-3.5=2.5 and range of 8-1.5=6.5, compared to Manufacturer A's IQR of 4.5-2.5=2 and range of 5-0.5=4.5.
500
A sleep time of 15.9 hours per day for a newborn baby is at the 10th percentile of the distribution of sleep times for all newborn babies. Assuming the distribution is normal with a standard deviation of 0.5 hour, approximately what is the mean sleep time, in hours per day, for newborn babies?
16.5 hours
500
Study hours and exam score have a correlation of 0.85. What percentage of variation in exam scores is not explained by the linear relationship with study hours?
r2=0.7225
1-.7225=.2775=27.75% can NOT be explained by the linear relationship with study hours.
500
The world's longest continuous commercial flight route spans nearly 9,500 miles and takes over 18 hours to complete. Which two global cities does this non-stop flight connect?
A. London and Sydney
B. New York City and Singapore
C. Los Angeles and Bangkok
D. Paris and Tokyo
B. New York City and Singapore