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 :
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?
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.
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?
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
5. An instructor decides to curve grades in a course depending upon the
percentile measures. Here are some summary statistics:
minimum 10.0% 25.0% median 75.0% 90.0% maximum
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
c 2006 Carl James Schwarz
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