Understanding Percentiles: Solving MCQ Homework

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In summary, the conversation discusses the concept of percentile and how it relates to test scores. A percentile is the value below which a certain percentage of observations fall. The 30th percentile refers to the score below which 30% of the reference group scored higher on the test. The correct answer is (b) because it falls at the 70th percentile, meaning that 70% of the reference group scored lower than the individual.
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UNknown 2010
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Homework Statement


If a 30 percent of a reference group scored higher than you did on a test, your score would be:
a)at the 30th percentile
b)at the 70th percentile
c)at the 71st percentile
d)at the 29th percentile
e)indeterminate from the available information

Homework Equations


I think it is c ?Please I need fast reply because my exam is very close

The Attempt at a Solution

 
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What do you think "percentile" means? Why do you think it is c?
 
  • #3
From wiki
A percentile (or centile) is the value of a variable below which a certain percent of observations fall. So the 20th percentile is the value (or score) below which 20 percent of the observations may be found. The term percentile and the related term percentile rank are often used in descriptive statistics as well as in the reporting of scores from norm-referenced tests. The 25th percentile is also known as the first quartile (Q1); the 50th percentile as the median or second quartile (Q2); the 75th percentile as the third quartile (Q3).

It should be (b) .. isn't it?
 

1. What is a percentile?

A percentile is a measure used in statistics to indicate the percentage of data points that fall below a certain value. It is commonly used to compare a particular data point to a group of data points.

2. How is a percentile calculated?

To calculate a percentile, first the data points are arranged in ascending order. Then, the desired percentile is multiplied by the total number of data points and divided by 100. The result is rounded up to the nearest whole number. This number corresponds to the position of the data point in the ordered list. If the number is not a whole number, the data points on either side of it are averaged to determine the percentile value.

3. What is the significance of percentiles?

Percentiles are important because they provide a way to measure and compare data points in a data set. They help to identify outliers, understand the distribution of data, and make informed decisions based on the relative position of a data point within a group.

4. How is a percentile different from a percentage?

A percentile is a measure of relative position within a group of data, while a percentage is a measure of a portion or proportion of a whole. Percentages are always expressed as a number out of 100, whereas percentiles can be any number between 0 and 100.

5. Can percentiles be used for all types of data?

Percentiles are most commonly used for quantitative data, such as numerical measurements. They can also be used for categorical data, but their interpretation may be less meaningful in this case. Additionally, percentiles are not applicable for data that is not normally distributed or has extreme outliers.

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