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**Unformatted text preview: **Multiple Choice Questions
Descriptive Statistics - Percentiles
1. Many professional schools require applicants to take a standardized test.
Suppose that 1000 students write the test, and you nd that your mark
of 63 (out of 100) was the 73rd percentile. This means :
(a)
(b)
(c)
(d)
(e)
At
At
At
At
At
least
least
least
least
least
73% of the people got 63 or better.
270 people got 73 or better.
270 people got 63 or better.
27% of the people got 73 or worse.
730 people got 73 or better.
2. A student discovers that his grade on a recent test was the 72nd percentile.
If 90 students wrote the test, then approximately how many students
received a higher grade than he did?
(a)
(b)
(c)
(d)
(e)
65
25
72
71
18
3. The following is an ogive on the number of ounces of alcohol (one ounce
is about 30 mL) consumed per week in a sample of 150 students.
1
A study wished to classify the students as light, moderate, heavy
and problem drinkers by the amount consumed per week. About what
percentage of students are moderate drinkers, i.e., consume between 4 and
8 ounces per week?
(a) 60%
(b) 20%
(c) 40%
(d) 80%
(e) 50%
4. Refer to the previous question. Problem drinkers will be classied as those
in the upper 10% of consumption. What is the approximate lower bound
for the consumption of problem drinkers?
(a) 15 oz
(b) 18 oz
(c) 17 oz
(d) 10%
(e) 90%
5. An instructor decides to curve grades in a course depending upon the
percentile measures. Here are some summary statistics:
Quantiles
minimum 10.0% 25.0% median 75.0% 90.0% maximum
final mark
10
48
55
66
78
87
93
Which of the following is FALSE?
(a) About 1/4 of the class received a score of 55 or less.
(b) About 3/4 of the class received a score of 75% or less.
(c) About 50% of the class received grades between 55 and 78.
(d) This method assigns grades relative to how others do in a class rather
than against an absolute standard.
(e) This method always has half of the class at or above the median
grade.
c 2006 Carl James Schwarz
2
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