99 points and brainliest only if you explain your

This is a histogram, write out the numbers each time there is an x.
27, 28, 28, 29, 29, 29, 30, 30, 30, 31, 31, 31, 33, 34
for median cross off the sides till you get to the middle
median = 30

The median is the middle number in a data set that is ordered from least to greatest. If there are two middle numbers in the data set then you would add the two middle numbers together and divide by two. (average them). So if we look at your data on the line plot and break it down we get:
27,28,28,29,29,29,30,30,30,31,31,31,33,34 
Step 1: Find the middle number. In this case there are two: 30 and 30
Step 2: Add them together. 30+30=60
Step 3: Divide by 2 (to get the average). 60/2= 30.
So in this case the median value of the data set would be 30.