Sophia Statistics Unit 3 Milestone complete.
Which of these statements best defines a stratified random sample? - CORRECT ANSWER-It is a
sample where the population is first broken into groups and then elements are randomly selected, in
proportion, from each group.
Which of the following data types will be continuous? - CORRECT ANSWER-The amount of snow
that fell last night.
A study in which results are measured without intervention from the researcher is called... - CORRECT
ANSWER-Observational study.
Which of the following best classifies the arrangement of bean bags? - CORRECT ANSWER-Low
accuracy and low precision.
Mike wants to find out the approximate income for professors in Michigan. He decides to randomly
select 50 professors who work for a college or university in Michigan and obtain their salaries.
What are the sample and the population of Mike's study? - CORRECT ANSWER-The 50 professors
that Mike interviews are his sample, and all of the professors who work in Michigan are the population.
James conducts a survey to study the relationship between cell phone use and grades earned during the
fall semester. James suspects that there might be a lot of other factors that affect grades besides cell
phones.
Which of the following could be a confounding variable in James's study? - CORRECT ANSWER-
Time spent studying.
Cindy measured and recorded the temperature of a liquid for an experiment. She used a poorly
calibrated thermometer and noted the temperature as 100.5 degrees Fahrenheit. The actual temperature
of the liquid was 95 degrees Fahrenheit.
The percent error in her calculation is... - CORRECT ANSWER-5.79%
On a candy production line, 3% of bags are overfilled. An employee randomly selects 100 bags and
finds that 5% are overfilled. A second employee takes another random sample of 250 bags and finds
that 2% are overfilled.
Which of the following explains why there is a difference between the two percentages? - CORRECT
ANSWER-Random error; the numbers were different due to variability inherent in sampling.
Rob sent an email survey to 2,000 cell phone owners asking about their satisfaction with their current
plan. Only 256 people returned the survey and they were predominately 18-24 years old.
