COMPREHENSIVE STUDY GUIDE 2026 SOLVED
◉ assume that a randomly selected subject is given a bone density
test. those test scores are normally distributed with a mean of 0 and
a standard deviation of 1. draw a graph and find the probability of a
bone density score between -1.66 and 1.66. Answer: the sketch is
bell-shaped with the area between -1.66 and 1.66 shaded to show
that it is between -1.66 and 1.66
◉ find the indicated critical value of z subscript 0.07 Answer: 1.48
◉ about _______% of the area is between z=-1 and z=1 (or within 1
standard deviation of the mean) Answer: 68.27%
◉ about _______% of the area is between z=-2 and z=2 (or within 2
standard deviations of the mean) Answer: 95.45%
◉ about _____% of the area is between z=-3 and z=3 (or within 3
standard deviations of the mean) Answer: 99.75%
◉ which of the following is not a descriptor of a normal distribution
of a random variable?
a. the graph of the distribution is bell-shaped
,b. the graph is centered around the mean
c. the graph is centered around 0
d. the graph of the distribution is symmetric Answer: c. the graph is
centered around 0
◉ A continuous random variable has a _____ distribution if its values
are spread evenly over the range of possibilities Answer: uniform
◉ which of the following is not a requirement for a density curve?
a. every point on the curve must have a vertical height that is 0 or
greater
b. the graph is centered around 0
c. the curve cannot fall below the horizontal axis
d. the total area under the curve must equal 1 Answer: b. the graph
is centered around 0
◉ which of the following does not describe the standard normal
distribution?
a. it is a normal distribution with a mean of 0 and a standard
deviation of 1
b. the total area under the curve must equal 1
c. the graph is uniform
d. the graph is symmetric Answer: c. the graph is uniform
,◉ which of the following would be information in a question asking
you to find the area of a region under the standard normal curve as a
solution?
a. a probability is given
b. a percentage is given
c. a distance of the horizontal axis is given
d. finding z subscript α Answer: c. a distance of the horizontal axis is
given
◉ what is the difference between a standard normal distribution
and a nonstandard normal distribution? Answer: the standard
normal distribution has a mean of 0 and a standard deviation of 1,
while a nonstandard normal distribution has a different value for
one or both of those parameters
◉ assume that adults have iq scores that are normally distributed
with a mean of 101.9 and a standard deviation of 16.1. find the
probability that a randomly selected adult has an iq greater than
133.3 Answer: 0.0256
◉ engineers want to design seats in a commercial aircraft so that
they are wide enough to fit 95% of all males. (accommodating 100%
of males would require very wide seats that would be much too
expensive.) men have hip breadths that are normally distributed
, with a mean of 14.7 in. and a standard deviation of 1.2 in. find p
subscript 95. that is, find the hip breadth for men that separates the
smallest 95% from the largest 5% Answer: 16.7 in.
◉ which of the following is not true?
a. the area in any normal distribution bounded by some score x is
the same as the area bounded by the equivalent z-score in the
standard normal distribution
b. a z-score is a conversion that standardizes any value from a
normal distribution to a standard normal distribution
c. a z-score is an area under the normal curve
d. if values are converted to standard z-scores, then procedures for
working with all normal distributions are the same as those for the
standard normal distribution Answer: c. a z-score is an area under
the normal curve
◉ where would a value separating the top 15% from other values on
the graph of a normal distribution be found? Answer: the right side
of the horizontal scale of the graph
◉ what conditions would produce a negative z-score? Answer: a z-
score corresponding to an area located entirely in the left side of the
curve