Find the quartiles for these data values: 5, 7, 7, 8, 10, 11, 12, 15, 17. a. q1 = 7, q2 = 11, q3 = 15 b. q1 = 7, q2 = 10, q3 = 13.5 c. q1 = 6, q2 = 9, q3 = 12 d. q1 = 7.5, q2 = 10.5, q3 = 13.5

The answer is B. Q1 = 7, Q2 = 10, Q3 = 13.5.
Solution:
Since the nine values are already arranged in ascending order, we can easily see that the median is 10. Hence Q2 = 10.

We can find the first quartile Q1 by getting the median in the lower half of the data 
     5, 7, 7, 8
that is, Q1 = (7 + 7) / 2 = 7

We can find the third quartile Q3 by getting the median for the upper half of the data 
     11, 12, 15, 17
that is, Q3 = (12 + 15) / 2 =13.5