To find the interquartile range (IQR) for Cole’s math quiz scores, we first need to arrange the scores in ascending order:
69, 72, 75, 77, 79, 81, 81, 85, 86, 92, 94, 99
Next, we find the median (second quartile), which is the middle value:
Median = (81 + 81) / 2 = 81
Now, we need to find the median of the lower half of the data (lower quartile Q1) and the median of the upper half of the data (upper quartile Q3).
For the lower half:
Q1 = Median of (69, 72, 75, 77, 79) = (75 + 77) / 2 = 76
For the upper half:
Q3 = Median of (85, 86, 92, 94, 99) = (86 + 92) / 2 = 89
Now, we can calculate the interquartile range (IQR) using the formula:
IQR = Q3 - Q1
IQR = 89 - 76
IQR = 13
So, the interquartile range for this set of quiz scores is 13. Therefore, the correct answer is 13.
