Quartiles and Interquartile Range

The video tutorial explains how to determine variability in test scores using the interquartile range (IQR). It compares the scores of Terry's and Luke's friends by calculating the IQR for each group. The process involves ordering the data, identifying quartiles, and computing the IQR by subtracting the first quartile from the third quartile. The tutorial concludes that Terry's friends have greater variability in their scores compared to Luke's friends.

What is the primary purpose of using the interquartile range (IQR) in data analysis?

• To calculate the sum of a data set

• To find the average of a data set

• To measure the variability of a data set

• To determine the median of a data set

What is the first step in calculating the interquartile range for a data set?

• Finding the mean of the data set

• Arranging the data in descending order

• Arranging the data in ascending order

• Calculating the sum of the data set

How many data points are in each quartile when dividing Terry's friends' scores?

• One

• Two

• Three

• Four

What is the value of the first quartile for Terry's friends' scores?

• 78

• 75.5

• 75

• 76

What is the interquartile range for Terry's friends' scores?

• 11.5

• 8.5

• 9.5

• 10.5

What is the first quartile value for Luke's friends' scores?

• 75

• 73

• 72

• 74

What is the third quartile value for Luke's friends' scores?

• 80.5

• 82

• 81

• 81.5

What is the interquartile range for Luke's friends' scores?

• 10.5

• 9.5

• 8.5

• 7.5

Which group of friends has greater variability in their scores based on the IQR?

• Cannot be determined

• Both have the same variability

• Luke's friends

• Terry's friends