Praxis Core Academic Skills for Educators: Mathematics (5733)Statistics and ProbabilityEasy
A teacher recorded the number of books read by students in a class over a month: 2, 5, 3, 7, 2, 4, 3, 5, 2, 6. What is the median number of books read?
- A4
- B2
- C4.5
- D3.5
Show answer & explanationAnswer & explanation
Correct answer: D. 3.5
First, order the data: 2, 2, 2, 3, 3, 4, 5, 5, 6, 7. There are 10 data points. The median is the average of the two middle numbers (the 5th and 6th values). (3 + 4) / 2 = 3.5.
Why the other options are wrong
- A. 4 is one of the middle numbers, but not the median of an even set.
- B. 2 is the mode, not the median.
- C. 4.5 would be incorrect, perhaps if the set was ordered differently or had a different size.
Median
The median is the middle value in an ordered data set.
- If the number of data points is odd, the median is the single middle value.
- If the number of data points is even, the median is the average of the two middle values.
- It is less affected by outliers than the mean.
Memory trick: Order first, then find the middle.