Honors Statistics
Midterm Review 2015
Name: _____________________________________________________________________________________
MULTIPLE CHOICE
____ 1. The city council has 6 men and 3 women. If we randomly choose two of them to co-chair a committee,
what is the probability these chairpersons are the same gender?
A) 4/9
B) 1/2
C) 5/9
D) 5/8
E) 7/8
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a) Are there any outliers in the data? Justify answer with calculations.
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11.
IQ test scores Scores on the Wechsler Adult Intelligence Scale (a standard IQ test) for the 20
to 34 age group are approximately Normally distributed with μ = 110 and σ = 25. For each
part, follow the four-step process.
(a) At what percentile is an IQ score of 150?
(b) What percent of people aged 20 to 34 have IQs between 125 and 150?
(c) MENSA is an elite organization that admits as members people who score in
the top 2% on IQ tests. What score on the Wechsler Adult Intelligence Scale would an
individual have to earn to qualify for MENSA membership?
Honors Statistics
Midterm Review 2015
12. Stats teachers’ cars A random sample of AP Statistics teachers was asked to report the age (in years)
and mileage of their primary vehicles. A scatterplot of the data, a least-squares regression printout, and a
residual plot are provided below.
(a) Give the equation of the least-squares regression line for these data. Identify any
variables you use.
(b) One teacher reported that her 6-year-old car had 65,000 miles on it. Find its residual.
(c) Interpret the slope of the line in context.
(d) What’s the correlation between car age and mileage? Interpret this value in context
Honors Statistics
Midterm Review 2015
13. Race and ethnicity The Census Bureau allows each person to choose from a long list of races. That is,
in the eyes of the Census Bureau, you belong to whatever race you say you belong to. Hispanic (also called
Latino) is a separate category. Hispanics may be of any race. If we choose a resident of the United States
at random, the Census Bureau gives these probabilities:25
(a) Verify that this is a legitimate assignment of probabilities.
(b) What is the probability that a randomly chosen American is Hispanic?
(c) Non-Hispanic whites are the historical majority in the United States. What is the
probability that a randomly chosen American is not a member of this group?
(d) Is the probability of being White and being Hispanic independent? Justify with
calculations.
14. Tall or short? Mr. Walker measures the heights (in inches) of the students in one of his classes. He
uses a computer to calculate the following numerical summaries:
Next, Mr. Walker has his entire class stand on their chairs, which are 18 inches off the ground. Then he
measures the distance from the top of each student’s head to the floor.
(a) Find the mean and median of these new measurements. Show your work.
(b) Find the standard deviation and IQR of these measurements. Show your work.
Honors Statistics
Midterm Review 2015
15. Standard Normal areas Use Table A to find the proportion of observations from a
standard Normal distribution that falls in each of the following regions. In each case, sketch a
standard Normal curve and shade the area representing the region.
(a) z ≤ −2.25
(b) z ≥ −2.25
(c) z > 1.77
(d) −2.25 < z < 1.77
(e) Find the number z at the 80th percentile of a standard Normal distribution.
(f) Find the number z such that 35% of all observations from a standard Normal
distribution are greater than z.