Describing Data
Which of the following displays is best suited for categorical data?
A. Box Plot
B. Bar Graph
C. Stem and Leaf Plot
D. Dot Plot
E. Scatterplot
What is B?
A personnel director studied the eating habits of employees by watching a group of employees at lunch. He wishes to see who buys in the cafeteria, who brings a home lunch, and who goes out. The study is categorized as:
A. a census
B. a survey sample
C. an observational study
D. a designed experiment
E. none of these
What is C?
States that if you have a population with mean μ and standard deviation σ and take sufficiently large random samples from the population with replacement, then the distribution of the sample means will be approximately normally distributed.
What is Central Limit Theorem?
Reducing the width of a confidence interval
What is increase sample size and decrease confidence level?
In skewed-right distributions, what is most frequently the relationship of the mean, median, and mode?
A. mean > median > mode
B. median > mean > mode
C. mode > median > mean
D. mode > mean > median
E. mean > mode > median
What is A?
An insurance company conducted a study to determine the percent of cardiologists who had been sued over the last 5 yrs.
The variable of interest is:
A. the doctor’s specialty, e.g. cardiology, obstetrics, etc.
B. the number of doctors who are cardiologists
C. all cardiologists in the American Medical Association directory
D. a random sample of 100 cardiologists
E. none of these
What is E?
If P(A)=0.4, P(B)=0.2, and P(A and B)= 0.08
Which is true?
A. Events A and B are independent and mutually exclusive
B. Events A and B are independent but not mutually exclusive
C. Events A and B are mutually exclusive but not independent
D. Events A and B are neither independent nor mutually exclusive
E. Events A and B are independent but whether they are mutually exclusive cannot be determined.
What is B?
What conclusion is drawn in a 95% confidence interval for μ is (6,9),if we test Ho: μ=10 vs. Ha: μ≠10 at α=.05?
What is reject Ho?
The Standard Deviation of the set
{5, 7, 7, 8, 10, 11} is 2. Which of the following sets also has a Standard Deviation of 2?
A. {4, 5, 8, 12, 14}
B. {2, 4, 6, 8, 10, 12}
C. {3, 5, 5, 6, 8, 9}
D. {10, 14, 14, 16, 20, 22}
What is C?
Explanation: Use 1-var stats in calculator :)
Using enough experimental units/people/subjects to distinguish a difference in the effects of the treatments from chance variation due to the random assignment
What is replication?
The probability that a person is over 6 feet tall if the mean height of her age group is 5’6” and a standard deviation of 10”
What is 0.273?
Explanation: normalcdf(6, 1E99, 5+6/12, 10/12)
A study of 20 teachers in a school district indicated that the 95% confidence interval for the mean salary of all teachers is ($38,945, $41,245). What assumptions must be true for this interval to be valid?
What is the distribution of all teachers’ salaries is approximately normal?
Lee’s z-score on his math test was 1.5. The class average was a 62.1 and the variance was 6.76. What was Lee’s actual grade on the test?
A. 60
B. 62
C. 64
D. 66
E. 68
What is D?
Explanation:
1.5 = (x-62.1)/(root(6.76))
solve for x getting 66
An insurance company conducted a study to determine the percent of cardiologists who had been sued over the last 5 yrs.
The population of interest is:
A. the set of all doctors who were sued for malpractice
B. the set of cardiologists who were sued for malpractice
C. all doctors
D. all cardiologists
E. all doctors who have malpractice insurance
What is D?
The probability that a shipment of 100 fruit will have no more than 6 rotten fruits if the probability that any one fruit is rotten is 0.04.
What is 0.8936?
Explanation: binomcdf(100, 0.04, 6) = 0.8936
Do boys perform better in math than girls? A randomly selected group of each gender were given the same math assessment.
What are Ho and Ha to determine if boys’ scores are higher than girls?
What is Ho: μb – μg = 0; Ha: μb – μg > 0 ?
The average grade on a math test given to two sections is 60.98. Section I has 27 students with a mean grade of 57.30. If the mean grade of Section 2 is 65.30, how many students are in section 2?
What is 23 students?
Explanation: (57.30*27+65.30n)/(27+n) = 60.98
solve for n and get 23
When inference about the population and inference about cause and effect can be made.
What is individuals randomly assigned to groups and individuals randomly selected?
National studies show that 14% of male teenagers and 12% of female teenagers will be involved in a major traffic accident while driving. What’s the probability that independent samples of 100 female teens and 75 male teens will have results that differ by more than 3% in either direction?
A. 0.042
B. 0.085
C. 0.42
D. 0.85
E. Cannot be determined
What is D?
Explanation: Both genders qualify for CLT because np and n(1-p) exceed 5
z = (.03-.02)/√(.14*.86/75 + .12*.88/100)
= 0.1938
Using normalcdf(.1938, 1E99) = 0.423
As both directions are needed so adding in the other tail (multiplying by 2) we get an answer of 0.846.
Which of the following statements about power are true?
I. Power = 1 - P(Type II Error)
II. An increase in sample size increases power.
III. A test with higher power is more likely to reject a false null hypothesis
What is I, II, and III?