Unit E: Statistics and Probability

Chapter 1: Statistics

Summary

Percentile Rank

• A percentile rank is a whole number between 0 and 99 that indicates the percent of the data that is less than a chosen data value.

• A percentile rank must be a whole number that does not include any fractions or decimals.
  

• The steps to find percentile rank are as follows:
• Step 1: Arrange the values in ascending order.
• Step 2: Count the number of values less than the chosen value to find b.
• Step 3: Count the number of values in the set of data to find n.
• Step 4: Substitute b and n into the percentile rank formula.
  
  
  «math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mi»percentile«/mi» «mo»§#160;«/mo» «mi»rank«/mi» «mo»=«/mo» «mfrac» «mi»b«/mi» «mi»n«/mi» «/mfrac» «mo»§#215;«/mo» «mn»100«/mn» «mo»%«/mo» «/math»
  

  where
  b is the number of values below the chosen value
  n is the number of values in the data set
  

  
  
  
  

Median

• The median, the middle value in the data, is the 50th percentile. This means 50% of the data will be less than the median.