Statistics and Data Interpretation: TEAS Practice Question with Answer & Explanation

Understanding the Median in Statistics

On the TEAS 7 Math section, you will frequently encounter questions regarding the measures of central tendency: mean, median, and mode. The median represents the exact middle value of a data set when the numbers are arranged in numerical order. It is the point where 50% of the data falls above and 50% falls below.

Step-by-Step Calculation

To find the median of the patient admission data (24, 33, 18, 51, 30, 29, 21), follow these steps:

1. Arrange the data in ascending order: This is the most crucial step. Many students make the mistake of picking the middle number from the original list without reordering it first.

   • Original: 24, 33, 18, 51, 30, 29, 21
   • Ordered: 18, 21, 24, 29, 30, 33, 51

2. Identify the middle number: Since there are 7 numbers in this data set (an odd number), the median is the single value located directly in the center.

   • 1st: 18
   • 2nd: 21
   • 3rd: 24
   • 4th: 29 (The Middle)
   • 5th: 30
   • 6th: 33
   • 7th: 51

The value 29 sits in the middle with three values to its left and three values to its right.

Why the Other Choices are Incorrect

• A) 24: This is the first number in the original (unordered) list. This is a common "distractor" for students who forget to reorder the data.
• C) 30: This is the middle number if the set is not correctly ordered or if a calculation error occurs when counting the middle position.
• D) 33: This is another value from the set, but it is located in the upper half of the data once ordered.

TEAS Concept: What if there is an even number of values?

In this example, we had 7 values (odd). If the nurse had tracked 8 days of data, you would take the two middle numbers, add them together, and divide by 2 to find the median.

Memory Tip

Think of the median of a highway—it is the strip of land or concrete right in the middle of the road. To find it in math, you must first "pave the road" by putting the numbers in order from smallest to largest.