What is the first quartile of this data set?11, 12, 13, 15, 17, 19, 22, 24, 29, 33, 38A.19B.13C.29D.11

To find the first quartile of a data set, you need to follow these steps:

1. First, arrange the data in ascending order. In this case, the data is already arranged in ascending order: 11, 12, 13, 15, 17, 19, 22, 24, 29, 33, 38.

2. Next, find the median of the data set. The median is the middle number when the data is arranged in ascending order. If the data set has an odd number of observations, the median is the middle number. If the data set has an even number of observations, the median is the average of the two middle numbers. In this case, the data set has 11 observations, so the median is the 6th number, which is 19.

3. The first quartile, also known as Q1, is the median of the lower half of the data, not including the median of the entire data set. In this case, the lower half of the data is 11, 12, 13, 15, 17. The median of this lower half is the 3rd number, which is 13.

So, the first quartile of this data set is 13. Therefore, the answer is B. 13.